Next Meeting: Friday, December 1, 2017
Open to the Public: TAAA encourages the public to join our general meetings held on the first Friday of the month in the Steward Observatory Lecture Hall (Room N210) on the U of A Campus.
CLICK THE LINK BELOW FOR MEETING DETAILS.
Next Meeting: Thursday, December 14, 2017
Location: USGS Building, Room 253 (520 North Park Ave)
Contact: Dennis McMacken
Come and learn your way around the night sky to add to your observing enjoyment. Meetings are on the second Thursday of each month.
Previous Meeting: Thursday, November 9, 2017
CLICK THE LINK BELOW FOR MEETING DETAILS.
Searching for diamonds in the cosmic haystack
An AFSIG Article by Paul Trittenbach
When I was young—between the ages of 8-18—I used to enjoy fishing. No, I’m not going to tell you about the one that got away, because they all did. I practiced catch and release. I considered myself to be a sport fisherman. I never acquired a taste for fish, so I always let them go. I enjoyed spending many hours reeling in a feisty trout or wrestling with a Large Mouth Bass. That was until I discovered that fish have numerous nerves in their mouths and every time I caught one I was inflicting serious pain on it for no worthwhile reason at all. After that, I could no longer consider myself a sport.
I never cared if I caught a fish. Sometimes I would spend time by a stream or a pond increasing my collection of reptiles and amphibians. Sometimes I would just explore the area in the spirit of Thoreau—learning from nature by watching nature. Sometimes I would read a book. Quite often I would never cast the line, but, instead, I would sit there pondering life, the universe, etc. At times I just sat there, simply without a care in the world. It was a good way to be by myself, immersed in a universe of thoughts. “Spoil the child and spare the rod,” if you’ll excuse the pun.
About the same time, around the age of eight years old, I received my first telescope. It was a four-inch Newtonian telescope on a manually operated German Equatorial Mount. The telescope was sold by Sears but made by Bausch & Lomb Corporation. If I had that telescope today I would probably be repulsed by the quality of its optics. However, when you’re a child, the ability to see details on the moon or objects in deep space is more important than the specifications of the telescope you’re using. I loved that telescope until I got into high school and set myself to the task of purchasing a telescope blank from Edmund Scientific and grinding my own mirror.
I had always been an enthusiast of nature. My very earliest recollections were memories of collecting rocks wherever I went, and taking them home to examine them under a magnifying glass. With every specimen, I ran to the family’s encyclopedias — yes you may remember what those are — to discover as much as I could about my minerals. In the same year a next-door neighbor gave me a microscope he had used in high school. My first look at a drop of water had changed my life.
My first love was with biology. I had a consuming fascination with living things; their construction, diversity and function both as individuals and as members of an ecosystem. I owned a copy of Hunting With the Microscope, an excellent book for amateur enthusiasts, and today it is a collector’s item. I spent a lot of time examining specimens and slides under my microscope. I also performed my first dissections in the fourth grade — using guidebooks and specimens purchased at a local hobby shop.
At the same time my interest in astronomy grew. As with most amateurs, my first observations were of the moon, Saturn and the Great Orion Nebula (M42). I remember how disappointed I was with my first observations of M42. Through my telescope, the nebula was not the gorgeous pastel colors I had seen in photographs in the encyclopedia. It was black and white. This disappointment had turned into a learning experience about how the human eye works. Saturn, of course, had captivated me, as I am sure it does so many amateurs when they see it for the first time.
I took the moon for granted, as I’m sure most amateurs do! I think it was because it was always there and so easy to see, so most of us never give it a second thought. Even when I participate in community outreach, the majority of star parties are held around the time of the new moon. It seems odd to me now, because the moon is such an easy target to find that I would think it would make an outstanding incentive for people to become involved in astronomy. In addition, the moon possesses no atmosphere to block our view of it, so we can always get highly detailed views of lunar structures. And last, the moon is a fossil of our early solar system and our planet. It has so much to teach us and there are so many reasons to continue exploring it.
The night sky is a pond—more appropriately a cosmic ocean— filled with many species to fish. I cast my telescope into its waters in the hope of reeling in an interesting catch. I make it sound a lot like reeling in a feisty trout or aggressive bass but in this pond there is always a catch—a really big catch! Generally, new amateur astronomers tend to go after the most obvious fish — targets like Saturn and the Orion nebula. It takes a little time, and involves a learning curve to find astronomical objects and become familiar with the diverse species and locations of them in the cosmic pond.
Once in a while an amateur astronomer may turn a pair of binoculars to M45, the Pleiades, and be surprised at how many stars he sees. If you are like me, you heard the story of the Pleiades as the Seven Sisters — all too many novices told you that the most stars visible to the unaided eye were seven — and hence the nickname. Until I developed an interest in astronomy, I carried that explanation with me. The name refers to the fact that seven of the nine of the brightest stars were named after the Seven Sisters of Greek mythology. In reality, from a good dark location, people have seen up to 14 stars with their unaided eyes—in this cluster of 1000 members. You will never capture all those stars in a pair of binoculars, or even a good telescope. We amateurs do not have the equipment necessary to survey all the stars in an open cluster such M45. However, we do have the quality and apertures of equipment to be able to survey all of the brighter stars and the nebulosity in which M45 swims.
My first experience viewing the Pleiades through a pair of binoculars was awesome. From the small town I grew up in, seven stars were visible to the unaided eye. I was blown away by how many stars I saw. You could even see some nebulosity surrounding them. Until that time, I had never noticed that the obvious things, the things that we take for granted, can be so amazing. I think that’s one of the reasons I regret not having spent more time studying the moon. Now, when I participate in star parties I make it a habit to show those objects that first enchanted me — in part because they are easy to find, even from urban areas, and because they demonstrate what is available to every individual in our night sky. They also never fail to impress a first time crowd.
The revelation of this catch is that there is far more than meets the eye. The unaided eye can inspire us with breathtaking wide-angle views of the cosmos. We see the Milky Way swim overhead and can be awed by the contrast between the dense lanes of stars and the dark nebulosity that squirms its way through the middle of this band. There are numerous other objects available to our unaided eye.
The unaided eye will be able to see man-made satellites as they pass overhead in all directions around our planet. We can also see meteors as they enter the sky and present a fiery show on their earthward plummet. We are able to see planets, albeit they will appear as star-like objects that move against the background of the celestial sphere — wanderers, as their name infers. Occasionally we may catch the space station, an eclipse, the green flash of the sunset, or in special cases the aurora borealis. At times we may be fortunate enough to catch a hairy star as it falls toward our sun.
Comet 45P/ Hond-Mrkos-Pajuskova (45P) will be skirting along the border of Leo and Leo minor as March begins. This comet has already made its closest pass with Earth on February 11, but will still show up in a small telescope on March 2. The new moon arrives a few days before that, at the end of February. So prime viewing time for this comet is going to be early evening between the few remaining days of February and the first few days of March. By March 5, the moon is already in first quarter and its bright beam may obscure the comet lying to the East.
Comet 45P is a short period comet from the orbit around Jupiter. This visitor returns every 5.25 years. This year it was known as the New Year’s Eve comet, approaching Earth to within 7.4 million miles and presenting itself as a spectacular binocular target. By now, it has moved off and is waning at a magnitude of around 10.0.
While I was still in high school, Pioneer 10 became the first man-made probe to reach Jupiter. At that time, Jupiter was known to have only four moons — the Galilean moons. Within a few years that number had jumped to 15. Because of Jupiter’s primordial gases there was a great deal of conjecture about the possibility of life on the planet. Even in his book Cosmos, Carl Sagan had speculated on the possibility of life on that world. Sagan’s book had conjectured that life forms, from protists to metazoans, might actually exist within the clouds of Jupiter. Today, I don’t think any scientists would support this hypothesis.
At 1,300 times the volume of Earth and more than twice the volume of all the other planets combined, Jupiter is the King of the planets. Located 450 million miles from the sun, Jupiter is one of four gas giants known in our solar system (Not considering the current theoretical planet nine). Although these planets dwarf the inner, rocky planets in size, they are composed primarily of basic gases and their overall density is less than that of Earth. Saturn, for example, possesses such a low density that it would float on a lake, if one large enough existed.
Jupiter is composed primarily of hydrogen and helium and a few primordial gases, such as methane and ammonia. These gases react with sunlight to create the multicolored bands in Jupiter’s atmosphere. Until analysis from the current Juno mission, present data suggests that Jupiter possesses no solid body at its core, but rather a liquid metal core of hydrogen. This liquid core demonstrates how thick and crushing the planet’s atmosphere is and that no human or machine could ever survive a plunge into it depths. To understand Jupiter, it becomes necessary for planetary scientists to probe the atmosphere with radar, gravitational analysis experiments and invisible wavelengths of light.
Jupiter rotates on its axis once every 9 hours and 52 minutes. It completes one revolution around the sun every 11.86 Earth years. Its major feature is the Great Red Spot, a giant swirling cyclone that has been known to exist since Galileo’s time, 400 years ago. The cyclone is three times the diameter of Earth! Observations over the past 30 years have demonstrated that the Great Red Spot is diminishing in size and color. However, new storms have appeared in Jupiter’s atmosphere during the same period.
Galileo was the first human to train a telescope on Jupiter in the year 1610. He discovered that it was another world within our solar system. He discovered four moons, known as the Galilean moons, and by observing them orbiting Jupiter he was able to prove the Copernican Heliocentric model of the solar system. He also was the first human to view the Great Red Spot. The four moons visible in our telescopes are the original moons discovered by Galileo and named in his honor.
Jupiter has 67 known moons, 54 possess names. Two of the Galilean moons have come under intense study by astrobiologists for their potential to harbor life. Europa and Ganymede possess the necessary ingredients for microbial life. Both moons are ice covered worlds that harbor saltwater oceans beneath their surface. Tidal forces and Jupiter’s magnetic field keep the moon’s cores active. Those tidal forces flex the cores to generate heat beneath the ice covered surface and mix the nutrients and chemical ingredients necessary for life. Crustal fractures in the surface allow the saltwater to be transported from the ocean below and create water plumes that contain the signatures of organic materials.
The Galilean moon of IO is the second most active body in the solar system. Upon the discovery of volcanoes, planetary scientists were stunned because they previously believed that worlds so distant and small would possess cores that have cooled too quickly to sustain any thermal activity. Tidal flexing between the planet and the outer moons of Europa, Ganymede and Callisto keep IO’s core active and generate volcanoes that spew plumes of sulfur up to 300 miles into space. Europa’s organic material is believed to be a composition of sulfurous compounds sprayed onto its surface by nearby IO.
It should be no surprise that Jupiter also possesses the largest magnetosphere of any planet in our solar system. This protective field extends 2 million miles sunward and 600,000 miles in the direction of Saturn’s orbit. This enormous magnetic field is so intense that the instruments of planetary probes would be fried if they remain in its proximity for too long. The current Juno probe to study Jupiter varies its orbits to swing closer and further away from the planet as it makes it studies. A heavy shielding of instrumentation and unique orbital geometries allow probes such as Juno to remain alive as they weave in and out to examine Jupiter and its moons.
Jupiter also possesses a faint, delicate ring system composed of dust. Although Galileo was the first to view the magnificent rings of Saturn in 1610, it was not until 1979 that Jupiter’s rings were seen. NASA’s Voyager 1 probe viewed Jupiter on its outward bound journey from the planet. As Voyager 1 looked back, it snapped an image of the planet eclipsing the sun and the faint 2 mile thick ring system was seen for the first time. The rings appear to be composed of ejecta from asteroid impacts with the inner moons. They are held in place by the four moons: Amalthea, Thebe, Adrastea and Metis. It wasn’t until recently that this ring system was viewed by both Earth-based telescopes and the Hubble Space Telescope.
Anything beyond the realm of our solar system constitutes deep sea fishing. This is deep space astronomy and it is populated with species as diverse and bizarre as the benthic fish of the deep ocean trenches. Here we can find species that are invisible and hidden from view, like the translucent species of fishes in the deepwater trenches. Here we find species that feed on the energy of others. Here we can find creatures that defy the imagination. The enormous powers of creation and destruction are found in these depths.
If you really want to turn on Dancing With The Stars, then you have to select a fine binary system like Algieba. Like all binary systems, Algieba dances to the music of the cosmos in a waltz that has played out for 13.8 billion years! Located in the constellation Leo, the lion, it is one of the most spectacular binary stars of winter. The two stars of this binary whirl around a common invisible center of mass over a period of 500-600 years.
Algieba (Gamma Leonis) is the second brightest star in Leo, after Regulus. This system comprises two orange giants. It is located 130 light years away, making it a celestial neighbor and an easy target. The primary star shines at magnitude 2.4 and its companion shines at 3.4. This binary star is moving through the galaxy at a velocity of 143,844.5 mph. As it hurls through the interstellar medium it creates a bow shock—similar to a boat moving through water.
Algieba’s main component is at least 180x the luminosity of the sun and 23x its diameter. Its companion star is at least 50x more luminous than the sun and 10x its diameter. Both stars are separated by 170 AU, so they are easy to split in a pair of binoculars or small telescope. Unlike the super red giant Betelgeuse, these stars are too low in mass to produce a supernova explosion and nebula similar to M42. Instead, in a last gasp of breath they will shed their outer layers to leave white dwarfs at their center — a star of carbon and oxygen about the size of our earth. The monuments to their deaths will be radiant, short-lived nebulae known as Planetary Nebulas (PN).
Located 1400 light years away in the constellation Hydra is the planetary nebula NGC 3242, the Ghost of Jupiter/Eye Nebula. Planetary nebulas are emission nebulas, formed when stars similar to or lower in mass than our sun exhaust their hydrogen fuel and are no longer able to sustain thermonuclear fusion. Instead of dying in a cataclysmic explosion to create reflection and emission nebulae, such as M42 in Orion, their matter rebounds off their stellar cores and into space as prismatic stellar clouds — a planetary nebula is formed.
Of the 1,100 planetary nebulas in the Milky Way no two are exactly the same shape. Most are classified as elliptical or bipolar, with lobes of gas protruding from opposite sides of the white dwarf that drives them. Less than 20% of the known planetary nebulas have a spherical shape. There are different theories for why the shapes occur, but the actual process of their creation is a source of continuous investigation. The most accepted theory for the variety of shapes is that they are driven by the magnetic fields of the stars at their center. Depending upon the angles from which they are viewed, some of these clouds take on the shapes of rainbow colored rings or spirals — such as the Ring Nebula (M57) in the constellation Lyra or the Helix Nebula (NGC 7293) in the constellation Aquarius — while others take on balloon-shaped lobes like those found in the Dumbbell Nebula (M27) in the constellation Velpecula.
The gases of the nebula are illuminated by the ultraviolet light of the hot white dwarf at its center. Unlike the emission and reflection nebulae, such as the Trifid Nebula in Sagittarius, the white dwarfs driving planetary nebulas erode their clouds away in as little as 10,000 years. Regardless of this short lifespan, NGC 3242 will be around long enough for us to enjoy. This is a stunning sapphire blue nebula that can be easily seen through a pair of binoculars or a small telescope. However, larger apertures will reveal more detail in NGC 3242.
Although the name Planetary Nebula implies “planet” it is a misnomer. According to legend, the term planetary nebula was coined in the 18th century by Sir William Herschel, who upon viewing his first planetary nebula confused it with Uranus — also one of his discoveries. The Ghost of Jupiter Nebula has absolutely nothing to do with the planet Jupiter.
Last month I devoted an entire article to open star clusters. This month I wanted choose one of the brightest and finest star clusters of the winter sky. Located 33,900 light years away, in the constellation of Canes Venatici, is the globular cluster Messier 3 (M3 or NGC 5272). Globular star clusters are dense associations of stars that are gravitationally bound together and traveling independently of the rest of the stars in our galaxy. These clusters are nearly as old as the universe itself. Where an open cluster consists of stars that are separated enough to resolve individual components in a telescope, a globular cluster is so dense that the core cannot be resolved into the individual components, even in professional telescopes.
Globular clusters can consist of hundreds of thousands to 1 million stars. These clusters reside in the halo of our galaxy, as opposed to the open clusters which reside in the spiral arms. Messier 3 consists of 500,000 members spread across the diameter of 220 light years. The members of this cluster are estimated to be 12 billion years in age. To put that into perspective, our sun is estimated to be 4.5 billion years old. Astronomers believe that star clusters are necessary for the production of galaxies.
M3 shines in a magnitude of 6.2 and is easily visible through a pair of binoculars. It will resolve into a bright central core that appears to resemble a snowball in space, a large aperture telescope will resolve more components. Because of its age, the population of M3 is predominately orange-red giant stars, that have burned through their hydrogen fuel and moved off the main sequence. However, there are several blue giants infused among this retirement community. Blue stars are young stars that cannot have developed within the same nebula that birthed the cluster. But when two stars merge their combined mass may form stars known as Blue Stragglers.These are the stars found in M3.
In Pennsylvania, where was born and lived for half my life, the night sky was awash with sky glow from the metropolitan areas. Escaping to the rural areas wasn’t much of a respite from the glare of the cities. The sky was gray and never achieved the black that I have experienced in the West. When I purchased my home on the Southeast side of Tucson, the night sky was very dark in comparison to the adjoining city. There were no shopping centers, very few schools and no grocery stores. The trade off of traveling a short distance for essentials was worth the price in exchange for the bounty of the cosmos available from my doorstep. With the cooperation of neighbors, porch lights were quelled and observing could commence. The time saved in traveling out of town to observe was gained as extra time under the stars.
It didn’t take much time for the city to encroach upon my pond. Within a few years, strip malls, grocery stores and schools sprang up like weeds on what once was a well manicured and verdant lawn. More and more, the city was moving in and the stars were moving out. Star clusters, galaxies and nebulas that were once very visible were now diluted by the sky glow of the surrounding businesses. UHC and light pollution filters helped to manage some of the light reflected from the pavement. But the damage was done, my pond had become polluted!
Over the years I have sought out better fishing holes—areas where the pond is less polluted. Even areas designated as dark protected sites are experiencing the crunch of encroaching cities. The club maintains a premier dark site near the Chiricahua National Monument (CAC). It is an excellent respite from the sky glow of the city and offers sensational fishing of the nocturnal pond. Recent studies have reported that 2/3 of the population of Earth cannot see the Milky Way from their locations. My hope is that city leaders will become more aware of light pollution and its ill effects upon human health and the health of plants and animals in the environment. Perhaps, one day, we will again be able to fish the night sky from all locations on Earth.
5,000 light years away in the constellation Monoceros lies the Rosette Nebula (Caldwell 49, NGC 2237). This is a faint but beautiful nebula which glows in the HII region at a magnitude of 9.0. The nebula is part of a larger region of nebulosity that includes several New General Catalog members: NGC 2238, 2239, 2244, 2246 and 2237 – which is the designation for the entire nebula region. Although the nebula can be viewed through a small aperture, you will want to employ a Hydrogen Beta (H-Beta) filter and a large aperture to tease out its details.
Caldwell 49 spans a diameter of 100 light years. This emission nebula is the nursery to 2500 type O stars. Most of the stars are enshrouded within the dense molecular cloud that comprises the nebula. Similar to the Eagle Nebula, optical data from the Digital Sky Survey reveals pillars (of creation) in which the young stars are born. The total estimated mass for the nebula is 10,000 solar masses.
Embedded in the nebula is a fine open cluster: NGC 2244 (Caldwell 50). The young, blue stars of this open cluster formed about 4 million years ago within NGC 2237. Their stellar winds are eroding away the nebula. It is the ultraviolet light from the young stars of this cluster that causes the gases of nebula to ionize and glow. The cluster is an exquisite collection of stars glowing at a magnitude of 4.4. It is easily visible through binoculars. However, NGC 2237 will not show up in binoculars.
The gas and dust molecular clouds take on the shape of a blossom, with the center area cleared out by erosion from the stellar winds of NGC 2244. The complex of nebulosity, consisting of the aforementioned New General Catalog members is a writhing mass of gas and dust lanes of varying degrees of illumination. Using the aforementioned H-beta filter or a UHC (ultrahigh contrast) filter will help to tease out details when viewed from a dark site such as the CAC facility. Even if you find that you are unable to see the nebula, the fine open cluster of NGC 2244 will be a treat unto itself.
Casting into the deep again, I seek out species of a different type and residing at greater depths. In the ocean’s abysses there are strange denizens that seem more like visitors from an alien planet than members of the same DNA heritage as us. It is as if the trenches opened up and released creatures from an Arthur Conan Doyle novel. Here, Winteria Telescopa (an excellent species for an astronomy article), a bug-eyed, jagged toothed predator, that looks like it swallowed a balloon, plies the waters. These same depths are shared by Bathynomus giganteus, an isopod and relative to the lobster that resembles a monster from the movie Deep Star Six.
In these depths, where the sun doesn’t even dare to tread, translucent Angler fishes hunt for prey using lures that resemble worms and attract their quarry with bioluminescence. The Sloane’s Viperfish possesses a jaw as big as his body, lined with long, pointy teeth that protrude well beyond his mandibles. This fish looks like the Sabertooth Cat of the abyss. Frill Sharks are predators near the top of the food chain at these depths. Their appearance resembles a flattened eel more than any shark that most of us would be familiar with. Perhaps this is an evolutionary adaptation to the intense pressures of the deep ocean. The list of weird and unbelievable creatures goes on.
Deep space, too, is filled with denizens that seem more like something out of a science fiction movie—too strange to be believable. There are magnetars and blazars, pulsars and neutron stars. There are giant stars and super giant stars—stars that turned into Frankensteins at the end stages of life, then erupt in horrific conflagrations that create supernovas. There are stars that cannibalize their companions before their gluttonous appetites cost them their lives in similar explosions. There are stars of carbon — blood red diamonds of the night. There are Active Galactic Nuclei (AGNs) that cause the stars of their immediate neighborhood to go into frenzied orbits, while they consume their energy. They are the vampires of the cosmos.
There are planets that wander interstellar space without a star to call their own. They are cold, frozen bodies, perhaps harboring remnants of lifeforms, frozen in time. There are super Jupiter gas giants, in orbit so close to their stars that their atmospheres are evaporating into interstellar space—being consumed by the mother that bore them. Other earths must exist, with bounties of life flourishing upon their faces. There are beautiful blossoms—the nebulas—products of the enormous explosions of the supernovas.
These, too, and all the other denizens of the deep space realm seem like creatures from an Arthur Conan Doyle novel. They are dinosaurs of the ancient universe, revealed to us by the speed limit imposed upon light. These beasts from the bowels of the universe demonstrate to us the enormous powers of creation and destruction that are the laws of the cosmos. They are the masters and creators in our universe. We can fear and simultaneously admire them.
In the constellation Leo, at a distance of approximately 30 million light years, lie three galaxies collectively known as the Leo Triplett, also known as the M66 group. This grouping of three large spiral galaxies are generally shown together at star parties as both a crowdpleaser and a wow factor. The triplett consists of the galaxies NGC 3628, M66 and M65. In the grouping, the three galaxies are tilted at different angles to the viewer, presenting the deceptive view that the galaxies may not all be large spirals. NGC 3628 is seen edge on. Obscuring dust lanes wrap across the plane of this galaxy, like a belt.
M65 and M66 are both tilted toward the viewer at angles that make their disks more obvious. Gravitational interactions between these galaxies have warped their disks and stretched out their spiral arms. In a telescopic view, the eye is unable to perceive the intricate details of the three galaxies. To view the Leo Triplett a wide-angle eyepiece is necessary. The Leo Triplett is accessible through a small aperture, such as a 4 inch telescope. The view of the three galaxies covers 500,000 light years.
Spanning a diameter of 95 light years across, M66 is the largest member of the Leo Triplett, and shines at a magnitude of 8.9. NGC 3628 and M65 shine at magnitudes 10.2. While the dust lanes of NGC 3628 are more obvious because they obscure the disk of the galaxy, M66 also possesses a thick dark lane that surrounds the outer portions of the galaxy. The gravitational interactions between these galaxies results in prodigious star formation. The title of facts from NGC 3628 spans 300,000 light years. M66 is the brightest member of the Leo Triplett.
Located 28 million miles from our galaxy in the constellation Virgo is a great spiral galaxy, Messier 104 (M104), the Sombrero Galaxy. If viewed from above, this 50 light year diameter galaxy would appear to be a spiral like our own Milky Way. But from the vantage point we have, slightly above the galactic equator, we see M104 as a large, bulbous halo of stars and gas that extends well above and below the galactic disk. From this vantage point M104 appears to be a mirrored, broad rimmed Mexican hat — and hence its name.
The Sombrero Galaxy is a member of the Virgo super cluster, the same cluster of galaxies to which our Milky Way belongs. This is a web of gravitationally bound galaxies with 2,000 known members. Sombrero Galaxy has an estimated mass equivalent to 8 billion suns and is rich and globular star clusters. There are an estimated 2,000 of them within the galaxy. The center of the galaxy is the home to a bright core of a 1 billion solar mass, supermassive black hole! In 2012 the Spitzer Space Telescope discovered that a second galaxy was embedded within M104. Galaxy mergers are not uncommon in the universe. Astronomers know that even the Milky Way is currently consuming at least two dwarf galaxies.
Until the 20th century astronomers believed that the Milky Way was the entire universe. Previous to that all patchy cloud-like structures were believed to be nebulae and part of our galaxy. In 1912 the astronomer Vesto Slipher observed M104 and hypothesized that it was moving away from our galaxy at a speed of 7000 mi./s. The enormous velocity of this nebula gave us clues that the universe was in fact much larger than our Milky Way and that separate structures existed outside of it.
Before Carl Sagan introduced the world to his series Cosmos in 1980, I used to write extra credit reports for my classes in high school. By the time I reached junior high school I began to realize that the universe was one interwoven tapestry of matter and energy that created everything we know. The creatures, the leaves on the plants they sat upon, the blades of grass, trees, the rocks, the stream and everything was precipitated from the hot soup of energy of the Big Bang. As the universe cooled down and formed matter, the subatomic particles evolved into the atoms, the atoms evolved into chemicals, the chemicals evolved into compounds and many of them became animated. At least one species was successful enough to stand on two legs, look up to the sky and ask questions about what all this was and what it meant.
In the same way that the electromagnetic spectrum is a continuum of light ranging from the invisible radio through the visible to the invisible gamma radiation, all of nature is a continuum from the precipitation of energy to matter, subatomic to atomic, atomic to chemical, physical chemical to biochemical, and life. This is a simplified explanation at best, but the relationship between physical, chemical and biological is the spectrum we call the universe.
My English teacher gave me a “C” for every one of my essays. Perhaps she found the material uninteresting. Perhaps she just found it boring. My science teachers, however, enjoyed my essays and gave me lots of extra credit for my enthusiasm, interest and insight into nature. When Carl Sagan arrived on PBS, he validated my assessments. The universe is one big fabric of interlaced members, each complementing and completing the other.
It is this relationship between the physical and biological world that keeps me intrigued and staring at both ends of the universe through my telescope and microscope. As I divide my time between the microscopic and telescopic realms I also recognize the obvious macro world of the metaphyta and metazoa—the multi cellular plants and animals of our visible, everyday world. I also realize that there are microscopic worlds that can only be accessed via an electron microscope and the subatomic that is only visible through machines like the Large Hadron Collider.
There are Go-To telescopes and star guides for helping us locate the fish in the celestial pond. Likewise there are sonar fish finders and lures that guarantee a catch with every cast. Perhaps that is cheating, but no hobby today is what it was when I was young. I also doubt that anyone owns a set of encyclopedias anymore. One great thing about fishing the night sky is that when you brag about your catch, and everyone believes it’s just a fish tale, at least there are photographs to prove it.
Over the years I have sought out better fishing holes—areas where the pond is less polluted. Even areas designated as dark protected sites are experiencing the crunch of encroaching cities. The club maintains a premier dark site near the Chiricahua National Monument (CAC). It is an excellent respite from the sky glow of the city and offers sensational fishing of the nocturnal pond. Recent studies have reported that 2/3 of the population of Earth cannot see the Milky Way from their locations. My hope is that city leaders will become more aware of light pollution and its ill effects upon human health and the health of plants and animals in the environment. Perhaps, one day, we will again be able to fish the night sky from all locations on Earth.
Whenever I cast into the cosmic pond I care if I catch a fish. Sometimes I will spend the time increasing my quota of newly observed celestial objects. Sometimes I will observe the night sky with my unaided eye, lying on my back and staring up at the sky, like a walk through the woods in the fashion of Henry David Thoreau. Sometimes I will leave the telescope behind and never cast a line into the pond. There are times when I will lie beneath the sky without a care in the world — lost in a universe of thoughts. Regardless of what method I choose to fish the nocturnal pond, there is only one thing wrong: at the end of the night, regardless of the size of the catch, I always have to throw it back.
An AFSIG article by: Paul Trittenbach
Grains of salt lie on a mat
In contrast to the velvet’s black
Suspended in their cosmos
They are orphans even as brothers…
I penned the opening stanza to that poem in 1982. Although I had interest in astronomy at the time, the poem was a philosophical treatment on how each of us assigns meaning to his life and not an ode to astronomy. I was reminded of this poem one afternoon while I was eating lunch. As I reached across the table for a platter of food, I accidentally spilled the saltshaker.
Throughout my life I have never been able to see shapes in the clouds. I never spotted a rabbit, a choo-choo train, an elephant— nothing other than a big puffy collection of condensed water vapor floating in blue sky. Up until the moment that I spilled that saltshaker, if someone had given me a Rorschach test, I would’ve seen nothing more than a huge splotch of ink on a piece of paper that couldn’t have been recycled. People who knew me found that ironic because I had exhibited artistic talents — photography, creative writing, painting and drawing — all of my life! Nevertheless, I always saw clouds and most other worldly shapes for what they literally were, not as abstracts.
In the second when the salt spilled out onto the table in front of me I became a student—albeit for a brief moment—in psychology. As the salt scattered across the table a very personal apparition appeared to me and without deliberation or hesitation I recognized it. For there, in front of me, wasn’t a rabbit, a choo-choo train or an elephant, but Messier 37. The ghost of Rorschach had reared up from the grave and taken his revenge upon me!
It is an interesting human trait — almost instinctual — that our brains habitually search for objects that are common to us. Recognizing human faces is one of our greatest idiosyncrasies and we seem to find them almost everywhere we look: the grills of cars, the man on the moon (or the woman on the moon, if you prefer), in landscape formations (some people even found a face on Mars created by the lighting on a mountain range), and even some foods. It seems that human faces — especially smiley faces — seem to abound. I have no doubt that many of us stargazers have seen smiley-faced asterisms in the stars.
So this month, in tribute to Dr. Herman Rorschach and completion of my lunch, it seems only fitting to offer a topic that will broaden your understanding of another cosmological object and hopefully bring a smile to your face. Open star clusters were one of the first types of cosmological objects to seize my attention as a beginning stargazer. They were so beautiful to my eyes, that to this day I liken them to diamonds, sparkling against the black velvet background of space. While some stargazers may succumb to adopting a “they all look alike to me” policy, when one delves into the physics and chemistry — the magic of the universe, if you will — they suddenly become intriguing.
Star clusters are associations of stars that are gravitationally bound to each other and moving independently of the rest of our galaxy. They fall into two categories — open and globular. Open star clusters are loose associations wherein the distance between the stars is so apparent that it is easy to resolve them in a pair of binoculars or a telescope. Open clusters generally contain hundreds to thousands of members formed from the same nebula with members of the same type and age. Globular clusters can possess tens of thousands or even hundreds of thousands of members. Globular clusters, on the other hand are densely packed associations wherein the nucleus is difficult to resolve into individual stars. They are also much old, nearly as old as the universe itself. Both types have separate histories and origins.
Located in the constellation of Canis Major is the open star cluster Messier 41. Also designated as NGC 2287, Messier 41 (M 41) is a congregation of 100 young, blue-white stars generously spread over a diameter of 25 light years. At 2300 light years distance the cluster is relatively close to earth. M41 is speeding away from us at 52,120 mph.
At 250 million years of age, the stars of M41 are young in comparison to stars like our sun, which is 5 billion years old and can burn for 10 billion years. These stars burn hot and bright and will expire within only hundreds of millions of years. Although the members are born out of the same stellar nebula, as they wonder through the galaxy they tend to pick up stragglers. Messier 41 is known to contain several red giant stars and at least two white dwarfs.
At star parties I compare Messier 41 to a single member of the Perseus Double Cluster — albeit with one-third the number of stars. These diamonds spread across the background of space offer a delightful view as they sparkle in our binoculars or telescope. In our brief lifetimes we will never be able to perceive M41s migration through the Milky Way. To us it will always be a permanent fixture in Canis Major.
Because the members of open clusters are of similar chemical composition and age, they generally possess the same properties and provide excellent laboratories for studying stellar formation. Some open clusters are so large — spread over many light years of distance — that they are visible to the unaided eye. Some examples of these include the Pleiades, the Hyades and M41. Many open clusters will easily resolve in a pair of binoculars. Some large clusters, such as M7 and IC 2391, have been described as far back as ancient times.
NGC 752 (Caldwell 28) is a gorgeous star cluster hidden in the constellation Andromeda. It is generally overshadowed by the Perseus Double Cluster, and the Andromeda and Triangulum galaxies, but I don’t think it is a cluster that should be overlooked. Although this cluster will resolve in a pair of binoculars it is best viewed through a telescope. The cluster contains 70 stars.
NGC 752 is a contradiction among open clusters. While most open clusters contain young stars — in the millions to hundreds of millions of years in age — the stars of this cluster are nearly 2 billion years old. Many of the most massive blue-white stars of this cluster have already moved off the main sequence and become red giants. Some of the most massive have already reached the end stages of their lives and become white dwarfs and neutron stars.
NGC 752 has a magnitude of 5.7 and is located 1300 light years away. It is a very large cluster, spread out over a large swath of space, approximately 75 x 75 arc minutes. It is the distance between the stars that gives away the cluster’s age. Over time, all open cluster disintegrate as their gravitational grip weakens. Use a wide-field eyepiece, sit back and enjoy viewing this sparkling cluster.
While some clusters, such as the Pleiades, have been described since ancient times, they are best viewed through binoculars or a telescope, which is able to resolve more of their individual components. Galileo was the first astronomer to describe 50 members among the Pleiades. Previous descriptions by ancient astronomers counted as few as 6 to 7 members. Nine of the brightest stars were named after the Seven Sisters of Greek mythology. Today, the Pleiades is known to contain 1000 members. Clusters of both types were classified by early astronomers as nebulae because early telescopes and the unaided eye were unable to resolve those patches of light into stars.
577 light years away, in the constellation Cancer is the open star cluster Messier 44 (M44). Also known as the Beehive Cluster, Praespe, Cr 189 or NGC 2632, it is one of the nearest open clusters to Earth and can be seen as a blurry patch with the unaided eye. M44 is known to contain 1,000 members, residing in a radius of 39 light years. The young stars of this cluster are between 600 to 700 million years old.
As mentioned before, most stars within a cluster are of similar age and type. But M44 is somewhat of an enigma, with its population consisting of various stars that simply don’t fit the model. The population of M44 is divided between M-class red dwarfs, which constitute 68% of its members; F, G and K spectral classes constitute 30% of the cluster’s population; and 2% are spectral class A stars. The cluster is also known to possess 11 white dwarfs and five giants of KOIII and GOIII have also been discovered.
The heaviest members have migrated toward the center of the cluster in a process known as Mass Segregation. While less faint members of the cluster now occupy the halo, or outer region of the cluster, the brighter more massive stars occupy the interior. The brightest members of the cluster possess a magnitude of 6.0 and are spectral class BO.
In 2012 astronomers discovered two planets orbiting two sun-like stars within the cluster — the first discovery of its kind. These planets are hot super Jupiters and orbit very close to their parent stars. Astronomy has come a long way since Galileo first turned his telescope on this cluster in 1609. At that time, he reported observing 40 members in the cluster. The ancients knew of this cluster and documentation of it reaches as far back as the Greek astronomer Claudius Ptolemy (AD 90-168), who described it as a nebulous mass within Cancer.
The Hyades ( Collinder 50, Melotte 25, Caldwell 41), in the constellation Taurus, is one of the closest open clusters to Earth at a distance of 151 light years. This spherical group of stars covers a diameter of 15 light years and shines at a magnitude of 0.5. The cluster consists of stars of the same age, chemical composition, origin and motion through space, providing a valuable laboratory for the study of open clusters. The stars of the Hyades are approximately 800 million years in age.
The cluster is located in the head of the bull, and visually appears to be associated with the red giant Aldebaran. Aldebaran, however, is not a member of the cluster. The cluster forms a V-shaped asterism consisting of five stars: Gamma, Delta 1, Theta Tauri, Zeta 1 and Epsilon Tauri. Of those stars, Epsilon Tauri is the first to be identified as having a planet — a super Jupiter.
The Hyades cluster is believed to have formed from the same stellar nebula as M44, the Beehive cluster. Both clusters appear to contain stars of the same age, composition and traveling in the same direction, from a similar point of origin. The Hyades is one of the few clusters of which the distance has been accurately measured, allowing astronomers to more accurately measure distances and scales in the universe. Anyone who enjoys viewing the Perseus Double Cluster should enjoy viewing the gorgeous blue-white gems of this cluster.
Open clusters may no longer reside within the molecular clouds of the nebulas that created them. One such example is M45, the Pleiades. The molecular cloud associated with M45 is not the progenitor of the cluster, but instead is one through which the cluster is currently moving. Because they are loosely bound together, most open clusters will disintegrate over a period of a few hundred million years. At times, the most massive open clusters survive longer.
Probably the most famous open cluster is Messier 45 (Melotte 22), the Pleiades in the constellation Taurus. I knew of it as a child, before I possessed an interest in astronomy. From the small town I grew up in, people would point to the cluster and tell me “it’s the Seven Sisters.” I remember their claims that seven stars were the most anyone with good eyesight could see, and they believed that was how the nickname came about. Until I developed an interest in astronomy, I carried that explanation with me. In reality, from a good dark location, people have seen up to 14 stars in this cluster of 500 members.
The Pleiades is a cluster of hot, young B-type stars of approximately 100 million years in age. The cluster seems to be immersed inside a reflection nebula, that was originally believed to be a remnant of the progenitor to this cluster and is known as the Maia nebula, named after the star Maia. However, this nebulosity is not the nebula from which Messier 45 formed, but a separate structure M45 is traveling through.
At a distance of 444 light years, M45 is one of the closest clusters to Earth. The cluster occupies a radius of 43 light years and possesses a mass of approximately 800 suns. Surrounding the star Merope is a bright reflection nebula known as Merope’s Nebula or Temple’s Nebula (named after its discoverer, astronomer Wilhelm Temple). Additional reflection nebulas have been discovered around the stars Electra, Taygeta, Celaeno and Alcyone. These nebulas are illuminated by the bright, hot blue stars of M45, which emit ultraviolet radiation to ionize the gases of the nebula. The Merope Nebula can be seen through a 4-inch aperture telescope under dark skies. M45 is currently breaking up, as the gravitational attraction between the member stars weakens. The cluster is expected to survive for only another 250 million years.
Estimates show that 25% of the objects in the Pleiades are brown dwarfs. Brown dwarfs are gas giants that range in mass from 15 × to 75 × the mass of Jupiter. These planets do not contain enough mass to create the core temperatures necessary to initiate thermal nuclear fusion. In essence, they are failed stars. The entire combined mass of these brown dwarfs is only about 2% of the total mass of M45.
Spitzer Space Telescope analysis of one of the stars, HD 23514, has resulted in the discovery of a large planetary disk orbiting that star. HD 23514 is a main sequence star that is less than 1 million years old. The Pleiades are also known to contain some white dwarfs. This creates a conundrum because astronomers cannot understand how a cluster so young can contain stars that have begun with enough mass to have reached the end of their life cycle in such a short period (100 million years). Astronomers believe that the stars are not stragglers, picked up by M45 on its trek through our galaxy. Stars with such low mass as the B-type members of M45 would usually take billions of years to evolve to the white dwarf stage. The only conclusion astronomers can form is that the stars started out so massive that they rapidly evolved to the white dwarf phase. ( Perhaps one day astronomers will confirm the discovery of a luminous A-class star with seven brown dwarfs orbiting it.)
The B-type stars of M45 do not possess enough mass to result in supernovas at the end of their life cycles. Instead, they will shed their outer shells to create planetary nebulas (PN). With its close proximity to Earth these planetary nebulas should be a spectacular sight for professional and amateur astronomers like.
The radiant gems of the open star cluster Messier 37 — my saltshaker cluster — in the constellation Auriga has often been referred to as one of the most brilliant and beautiful open clusters in the winter sky. Of the three clusters of the constellation — M36, M37 and M38 — M37 is the brightest. The cluster possesses 150 members at a visual magnitude of 12.5 or less. Collectively, this cluster shines at a magnitude of 6.2. Of the three clusters in Auriga, M37 and M36 are visible to the unaided eye from a dark location.
The members of this cluster are relatively young, at around 300 million years. But scattered among the blue-white stars that dominate this cluster there are at least a dozen red giants and some white dwarfs. These are likely stragglers picked up by M37 on its trek through the Milky Way. CCD observations of the cluster down to magnitude 22.0 have revealed that it has a population of more than 14,000 members.
Messier 37 (M37, NGC 2099) is located 3,600 light years from Earth and spans a diameter of approximately 25 light years. When viewed through a pair of binoculars or a small telescope the core of the cluster reveals about a dozen stars down to magnitude 10.0. By employing averted vision, dozens of stars surrounding the center of the cluster come into view. The center of the cluster is dominated by a bright red giant.
There are worlds of salt and sand
scattered throughout the universe
where upon them someone may stand
questioning his place and worth
Throughout history, salt has played a significant role in society. Salt has been used to purify, season and as a form of currency—every bit as important as gold. In the Bible, salt is referenced 30 times and Jesus is quoted as telling his disciples “Ye are the salt of the earth,” a reference to a good and worthy person. But some historians believe that Jesus’ reference to “salt of the earth” was not about the goodness and worthiness of the person, but as a reference to the fact that some types of salts — including magnesium salts — have been used as fertilizers since ancient times.
Ancient Greeks traded salt for slaves and when a salve was not worth his price it was said that he “was not worth his “salt.” It was a scarce commodity in ancient times, having to be extracted either from surface outcrops, such as dried-up inland seas, or boiled from brine. Some historic references claim that the ancient Romans paid their soldiers partially in salt — and our modern word for salary is derived from solarium argentum, a soldier’s pay. This claim is refuted by historians who claim that by the time of ancient Rome, processes for extracting salt from boiling brine had been perfected. But, today, in Ethiopia, many people are paid in pressed bars of salt.
Some historians have traced the use of salt back to prehistoric times. Ancient trade routes were established by the Romans, the Phoenicians and the empires of the Mediterranean along salt trails. The Romans are said to have salted their leafy greens and vegetables, leading to the modern-day word of salad. The word salvation is supposedly derived from Catholic religious rituals in which covenants were often sealed in salt.
Salt is literally a sustainer of human and animal life. Sodium chloride, the chemical that we identify as table salt, provides ions in solution that are essential for nerve and muscle function as well as regulation of body fluids. It plays a significant role in blood volume and blood pressure. But when it is taken in excess amounts it can lead to serious health conditions that can damage the heart, kidneys and lead to strokes. All terrestrial life evolved from the ocean and in a normal concentration the salt content in our bodies is the same as that of seawater.
Salt and sand play both metaphorical and literal roles in my poem. In previous paragraphs I outlined the role that salt has played in human history — both literally and figuratively. Oxygen is the most abundant element in the earth and it is no surprise that combined with silicon it forms the most abundant mineral basis for rocks. Silicon dioxide also plays an important role of trace element — albeit in very minute amounts — within the human body. It has often been said that there are more stars in the universe than gains of sand on all the beaches of the world. Like salt, silicon dioxide, and more specifically, silica, plays a significant role in our materials and technology.
I don’t believe that the jury is in on whether or not intelligent life can exist on planets in star clusters. Open star clusters contain stars too young, and with a limited lifespan, to be capable of developing the planets necessary to promote the evolution of intelligent life. However, astronomers are still debating whether or not intelligent life may exist on planets in globular clusters. Although my poem was not astronomy themed, it contains stanzas that could easily fit a discussion about intelligent life on other worlds. Certainly we stand upon a grain of sand, one of possibly billions in the universe, gazing in awe into the cosmos and pondering our existence.
Ever since I received my first telescope at the age of eight I have looked up into the night sky and wondered if there was intelligent life on other worlds. No, it wasn’t because I was concerned that we might be alone in the universe. I wondered if intelligent life elsewhere endured similar problems to mankind. Did they suffer from the pettiness, the greed, the desire to overpower and the lust to conquer that we do? Do they have pollution in their air and water? Do they suffer from poverty and disease? Do they have wars that threaten them with extinction, or have they solved the complex problem of cooperation?
Astronomers, philosophers and men of the cloth have all stared skyward asking the same questions of existence and hoping to arrive at slightly different answers. I imagine that the Jesuit priests of the Vatican Observatory are hoping to look into the face of God for the answers to our existence, while astronomers are hoping to reveal the ultimate equation for everything, and philosophers simply want the answer to the meaning of life. Astronomy is definitely a humbling experience, wherein we deal with such enormous distances, sizes and power that it is mind-boggling! No matter how you dice or slice the numbers, the universe is huge and we are definitely small. Perhaps it is this revelation of scale that drives us to seek an answer to the meaning of our existence.
I don’t pretend to have an answer to the meaning of existence. In all my years in amateur astronomy I have never stood at my telescope and pondered it. I am a fan of the universe. I marvel at its elegance and how everything in existence can be constructed out of the evolution of the hydrogen atom into all the atoms, chemical compounds and structures found in nature. While each structure may appear to be different, it is simply an optical illusion caused by a rearrangement of the building blocks of the cosmos. Perhaps Rorschach is rolling in his grave with laughter now that I realize how much my poems’ analysis of the way each of us assigns a meaning to our lives is similar to the very questions that our species has asked ever since the very first human gazed upon the night sky.
Ironically, I have never referred to the stars as grains of salt in any my conversations. Today, I liken them to diamonds against the velvet background of space. At one time, however, salt was every bit as valuable as diamonds are today. But for the time being, I will stand at my telescope and gaze upon those grains of salt on velvet black. All of the stars of the universe, created from the same Big Bang, are living out their lives in this universe as galaxies, star clusters and solar systems — they are orphans, even as brothers.
On a good winter night, take it upon yourself to get outdoors under a black velvet sky and look at the glittering grains of salt in the open clusters of the Milky Way. Perhaps you will just simply marvel at the radiant beauty of these cosmic gems. Perhaps you will visualize the elegance of chemistry and physics. Perhaps you will find some familiar personal shapes or even smiling faces. Whatever you see when you gaze upon them, I guarantee that you are not crazy.
An AFSIG article by Paul Trittenbach
In the classical Niels Bohr model of the atom, the one that we were taught in first-year chemistry, electrons whorl around the nucleus in what appears to be an analog of a miniature model of our solar system. In the four dimensional atom (I have included the time dimension) electrons occupy a fuzzy area— the electron cloud— of a specific orbital. These orbitals are not arranged in a “plane of the ecliptic” flat fashion like the planets in our solar system (please note that many minor planets of the Kuiper Belt do not occupy the plane of the ecliptic) but within clouds that appear balloon-like and spreading in all directions from the nucleus. To make it clear, the electron cloud is not a physical bellowing, misty mass of suspended particles or smoke but the area of uncertainty occupied by the electron. The true whereabouts of the electron is unknown; defined by the Heisenberg uncertainty principle which states that we can measure one of a subatomic particle’s properties — location, speed or direction — but not all three. Measuring one will change the others.
Each orbital of the atom has a specific maximum number of electrons that can occupy it. Within the atom electrons jump from one orbital level up to another and then return back again, analogous to children bobbing around on a trampoline. As electrons return to their original ground state (the children descending to the head of the trampoline) they release a packet of energy known as a photon—light. The activities and numbers of electrons of each chemical element or compounds release a specific light signature that helps us to identify that chemical or compound and the nature of its behavior. These light signatures encompass a broad gamut of energies known collectively as the electromagnetic spectrum.
Over millions of years, humans and other animals have evolved to develop specialized photon receptors: eyes. Although they are an ingenious invention, eyes are limited to a very narrow range of the electromagnetic spectrum that we call the visible spectrum. This is the bright, white light that is emitted by our sun and glows in the 5000°K temperature region. It is needless to say how invaluable this adaptation has been for us. Moving about on the surface of the Earth, this visible light range has helped us to perceive and adapt to our world, and manipulate our surroundings to our desires. For the majority of human existence, our eyesight provided us with evidence of reality and “proof” of matters that required validation.
Light has been so essential to our reality that over the millennia humans have coined a number of phrases to express just how important it is. Everyone knows “seeing is believing” and that light is truth. “I am the light…” Christ is quoted as saying in the Bible. “Children go into the light” is expressed by the psychic in the in Steven Spielberg’s Poltergeist. Light is both truth and good. When we want to be deceptive or keep something from someone else we keep them in the dark. Monsters lurk in the dark and hide under our beds when we are children. Scary movies play upon this to take advantage of our strongest primal fears. But we live in an age where we know “seeing” is not always believing and sometimes when we see something it is merely a ruse to keep us in the dark.
The curiosity and ingenuity of humans has led us to the discovery of the electromagnetic spectrum and the pursuit to identify exactly what light is and to understanding its behavior. But more importantly it has also led us to the awareness that seeing something with our eyes alone is not always the whole story. Nature does, in fact, keep most of her secrets hidden in a realm way beyond the limitations of our eyesight.
Located 1500 light years away in the constellation Orion is IC 434 and the associated Horsehead Nebula. The Horsehead Nebula itself is a dark absorption nebula that is very difficult to spot. Large aperture, an H-beta filter and careful hunting will help you to find it nested inside of its companion emission nebula, IC 434. IC 434 is believed to be excited by the star Sigma Orionis, the star at the eastern end of Orion’s belt. IC 434 appears as a cloud with streamers, of gas rising from it. In images the cloud glows pink because of ionized hydrogen gas. The streamers are believed to be the result of magnetic fields produced within the nebula. The Horsehead itself is a projection of the cloud and is a protostellar factory similar to the Pillars of Creation in the Eagle nebula.
In my research I have discovered that the expression “a horse of a different color” has been attributed to at least three different sources: Shakespeare and medieval knights. One source claims that Shakespeare was the first to use the reference of “a horse of that colour” to refer to the same matter, in his play Twelfh Night.
My purpose is, indeed, a horse of that colour.
And your horse now would make him an ass.
Ass, I doubt not.
O, ’twill be admirable!
Twelfh Night, Act2, Scene 3
According to that source, Shakespeare used this phrase several times in his writing, which the source believes indicates that the phrase “A horse of a different color” originated before Shakespeare’s time.
In today’s parlance the phrase refers to something of a different matter altogether. Since it’s unlikely that the true historical origins of the phrase will ever be known, I will lay claim to it in this article. I am employing the expression “a horse of a different color” to briefly describe the electromagnetic spectrum and its relationship to astronomical objects. In this example I employ the great stallion in IC 434.
Radio waves reside at the low-end of the electromagnetic spectrum and range in size from one millimeter to over 96 kilometers in length. They are the longest wavelengths of the electromagnetic spectrum and the lowest detectable energy. Because of their size, radio waves are unaltered by other types of light. They are also able to pass through most materials uninhibited and unaffected by the molecules of the substances through which they pass.
We are familiar with radio waves and their applications to communications, which includes radio, television and cellular telephones. Radio sources are naturally occurring too. On earth, lightning produces radio waves and in space all celestial objects emit them as products of atomic interactions. Nebulas, such as the Horsehead Nebula, appear as clouds of gas and dust in optical instruments. These clouds visually occlude stars and protostellar matter and prevent observations of objects within them.
Because of their long wavelengths, radio waves require large metal receiving dishes to focus them and achieve resolution. Today’s radio telescopes are combined into arrays of multiple large dishes — such as the Very Large Array (VLA) in New Mexico and the Atacama Large Millimeter \ Submillimeter Array (ALMA) in Chile. Radio telescopes can push back the veil of secrecy in celestial objects and reveal information about the location, density and motion of the gases — including hydrogen, which constitutes three quarters of all matter in the universe — in addition to studying Astrochemistry, the chemistry of astronomical objects. It reveals nascent stars forming within the hydrogen columns of gas and dust that create the fingerlike extensions seen in close-ups of nebulae.
Of course, radio astronomy is applicable to all celestial objects and in my example I use IC 434 to demonstrate how these invisible wavelengths of light can help us to examine the structures of the universe. IC 434 is an emission nebula over which a dark absorption nebulosity is laid. The structures of celestial objects beyond the visible spectrum of light are color-coded in Representative Colors (sometimes referred to as false color) by scientists to help them understand the processes and composition of them.
Using the 30m radio telescope near the Pico del Veleta in the Spanish Sierra Nevada, astronomers have discovered hydrocarbon molecules within the Horsehead Nebula. Here on earth, these molecules provide humans with their primary source of energy (in addition to their primary problems of global climate change). Examinations have revealed 30 different hydrocarbon molecules — more than 200 times the total hydrocarbons available on earth! These molecules, like much of the nebula itself are eroded away by the ultraviolet light from the star that powers of nebula.
Microwaves are wavelengths of electromagnetic radiation that range from 1 millimeter to 1 meter in length. Some sources include them within the radio wavelengths of the spectrum, however their name indicates that they are smaller, more compact waves than those of typical radio broadcasts. While microwaves do have applications in communications, such as cellular and satellite, in addition to microwave cooking and radar, microwaves are also emitted by cosmological sources. Radio telescopes, such as the Atacama Large Millimeter \ Submillimeter Array in Chile are able to tune to the smaller wavelengths and study everything from the cosmic microwave background, to galaxy formation, stellar and planetary formation and the composition of planetary atmospheres within solar systems.
In nebulae, such as IC 434, microwave analysis can be used to study protoplanetary systems and their formation and to discover and analyze organic compounds. Combining the light of x-ray and visual astronomy to microwave imaging provides a more complete picture of how galaxies, nebulae, supermassive black holes and all other cosmological objects work. Microwaves can reveal invisible extensions in cosmological objects, such as the outpouring gases from supermassive black holes, in greater detail than other wavelengths of light.
Just below the visible red portion of the spectrum, between wavelenghts of 30 centimeters and 740 nanometers (a nanometer is 1 billionth of a meter), resides infrared light. This bandwidth covers more than 1000 times the range of the visible spectrum of light! We are familiar with infrared light as heat that warms our skin on a sunny day or rises up from our cooking devices. Some sources divide the infrared portion of the spectrum into several divisions but astronomers generally speak of infrared as near and far.
At the near end of the infrared spectrum lies light of low intensity. We generally use this light for broadcasting through fiber optics and controlling channels from a remote, such as your TV remote. Everything operating at a temperature of about 268°C (514°F) and above emits infrared radiation. More than half of the energy coming from our sun is in the infrared wavelengths. Even the light bulbs in your home emit most of their energy as infrared light.
Infrared light is easily absorbed by water vapor, therefore astronomers have to place telescopes in very high and dry locations in order to be able to detect and analyze the near infrared portion of the spectrum. The far infrared portion of the spectrum never passes through our atmosphere. Therefore, the best location for analyzing the infrared spectrum is from space-based telescopes. Over the past few decades advances in CCD imaging has allowed for detailed observations of celestial infrared sources.
Due to its longer wavelengths, infrared light is subject to less scattering through the gases and dust of interstellar space. This allows astronomers to make discoveries inside of structures such as galaxies and nebulae which would otherwise be obscured by the clouds. Infrared light can also be emitted by objects that are otherwise too cool to radiate in visible light. Because of this property astronomers have discovered objects such as the streamers of dust in IC 434 and other nebulae, in addition to asteroids, comets and other objects too cool to be picked up by visible light astronomy. Infrared detection has allowed astronomers to cut through the dust lanes of the Milky Way and reveal structures on the opposite side of our galaxy. Infrared astronomy is also applicable to the study of planets and Astrochemistry.
In the visible light spectrum, our eyes see IC 434 as a grayscale image. Our eyelids are designed to flicker several times per minute, like the shutter on a video camera, to help us see moving objects; to avoid becoming prey or to capture prey. This adaptation to survival on planet Earth has rendered us virtually colorblind to deep space objects. Unlike the shutters on our cameras, our eyelids do not remain open long enough to saturate our retinas with the light coming from nebulae such as IC 434.
Our cameras, however, are capable of leaving their shutters open for lengthy periods of time, in addition to being sensitive to fainter emissions, and saturating the photoreceptors of our digital chips with the low intensity light of deep space objects until we can render an image of intense color. This compensation for nature’s adaptation to survive on our planet has allowed us to study and appreciate these cosmological horses of a different color. Where a nebula such as IC 434 is spread out over such a broad swath of space, reducing our eye’s perception of it, our time exposures compensate and gift us with an awesome image that we only wish we were capable of seeing in the full colors of the cosmological palette. Moreover, these colors reveal a great deal about the mechanisms of nebulae and the stars that created them.
Undoubtedly, the discovery of the spectrum and the invention of photography which followed (the discovery of the Camera Obscura not withstanding) led to a craving among scientists to find out whether more secrets of the cosmos lay hidden deep within the invisible parts of the spectrum. Even the early black and white plate photographs revealed previously hidden characteristics of cosmological objects. In addition, the beginning amateur astronomer must realize, at least to some degree, the impact that photography has had upon astronomy. One can only imagine the amazement that astronomers themselves felt when they looked upon those early photographic plates.
But this does not devalue visual observation! In the centuries preceding photography — including the centuries preceding the development of the telescope — careful observation honed the analytical skills of astronomers and opened up a whole new universe to humankind. There is a special visceral experience that only visual observation can offer a type of “seeing is believing”. If you are a casual observer — that is if you are not an astroimager — then you have to tease out details in celestial objects with patience and persistence. IC 434 and the Horsehead Nebula will challenge your patience and persistence.
Another source says that the phrase “A horse of a different color” originated from jousting medieval knights who rode horses of different colors to identify themselves to their supporters — much in same way as modern sports teams wear different uniforms to identify themselves to their fans. The third reference says that the phrase derives from the gambling habits of medieval knights. “A horse of a different color” implied that the opposite gambler or team had won a bet.
Spanning a range of 380 nanometers to 10 nanometers is the ultraviolet portion of the spectrum. Ultraviolet light falls into a frequency range between visible and x-rays. We are familiar with some of this spectrum because of the warnings issued about damage to our skin and cancer. However, the majority of ultraviolet light does not reach Earth’s surface. Ultraviolet light is divided into three sub-bands: UVA, UVB and UVC (far ultraviolet). The wavelengths from 10-180nm range propagate only in a vacuum and are referred to as extreme wavelengths. UV radiation possesses enough energy to cause atoms and molecules to ionize by stripping off electrons that would otherwise keep them bound to each other. It results in the breakdown of chemicals that would otherwise remain stable. This makes UV light harmful to life but renders the colorful gases we see in images of nebulas, such as IC 434.
Since most of the UV frequencies are absorbed by the upper atmosphere, ultraviolet astronomy is performed by satellites, either in Earth orbit or in space. In addition to the sun, numerous celestial objects emit ultraviolet light. Large young stars are a significant source of these wavelengths. Ultraviolet light helps to reveal details in planetary atmospheres and highlight filaments of gas that can be found in nebulas. Ultraviolet measurements of inter-stellar gas clouds is used to understand densities, temperatures and chemical compositions of stars and galaxies. If the Milky Way galaxy was viewed in ultraviolet light most of the stars would disappear.
My first recollection of the expression “A horse of a different color” is from the 1939 movie the Wizard of Oz, starring Judy Garland as Dorothy. When Dorothy and her dog Toto, along with the Straw Man, the Cowardly Lion and the Tin Man arrive at the gates of the Emerald City they have trouble convincing the guardian of the gates to let them in. They finally convince him that they just have to see the wizard, to which he replies:
“Well, bust my buttons! Why didn’t you say that in the first place? That’s a horse of a different color! Come on in!”
Once inside the Emerald City, they find themselves riding on a horse drawn carriage. The horse changes colors as it pulls them around the city. Dorothy remarks that she has never seen such a horse before and asks the driver what kind of horse it is, to which the driver responds:
“No, and never will again, I fancy. There’s only one of him, and he’s it. He’s the Horse of a Different Color you’ve heard tell about.”
Ranging above the ultraviolet spectrum between wavelengths of 10 nm and one pico meter (a pico meter is one-trillionth of a meter) are the x-ray bands of the spectrum. X-rays are divided into two categories: soft and hard x-rays. Soft x-rays range in wavelengths of 10 nm to 100 pm and hard x-rays range in wavelengths of 100pm to 1 pm. Hard x-rays reside in the same wavelength of the spectrum as gamma rays. Gamma rays, however, are produced by atomic nuclei while x-rays are produced by the acceleration of electrons.
We are familiar with x-rays in their applications to medical diagnostics. X-rays are also used in the industry. As an astronomical tool, x-rays are used to examine neutron stars, pulsars, black holes or galaxy clusters. Massive, compact stellar remnants such as these strip material from companion stars and create discs of extremely hot gases emitting x-rays, as the gases spiral inward toward the cannibalizing star.
Our sun also produces x-rays within the chromosphere but it is not as strong as source as these other stellar objects. O and Wolf-Rayet type stars create strong solar winds, much stronger than those of the sun. These winds create shockwaves that heat their plasmas, which in turn emits x-rays. Long-term observations of these stars have revealed that the solar winds are confined by magnetic fields.
X-rays are damaging to living tissue. So while they are used in medical diagnostics and applications to the treatment and cure of cancer, they also pose a harmful threat and must be used judiciously. Fortunately for us, our atmosphere absorbs the x-rays from the sun and other celestial sources. The water vapor within our atmosphere is opaque to x-ray photons. As a result, it is necessary for us to build satellites and detect x-rays from orbit or deep space.
Occupying a frequency of less than 100 pico meters, in the hard x-ray range of the spectrum, are the gamma rays. Gamma rays are usually produced through the nuclear reactions of fusion, fission, alpha decay or gamma decay. Astronomers generally define gamma rays by their energies without specifying the processes that created them. Extremely powerful outbursts of gamma rays, known as Gamma Ray Bursts (GRBs) are energies exceeding those of radioactive decay. Astronomers believe that these GRBs are produced by the collapse of stars into explosions known as hyper-novas.
Because gamma rays are unable to penetrate Earth’s atmosphere — an advantage to life on our planet — it wasn’t until 60 years after their discovery that theory of gamma ray production by cosmological objects was confirmed. In 1963 the United States Air Force launched the Vela satellites with the mission of monitoring nuclear tests by the Soviet Union during the height of the Cold War. The satellites flew at altitudes of up to 65,000 miles above the earth. The Vela satellites carried detectors not only capable of finding gamma rays but determining the direction they were coming from. Much to the scientists’ surprise, they were finding gamma rays from outside of our solar system. They had discovered the first Gamma Ray Bursts (GRBs).
In addition to space-based probes, gamma rays are detected by measuring the interactions of cascades of particles as they pass through the upper atmosphere. Through this analysis, astronomers are able to trace the gamma rays back to their source of origin. Astronomers also use gamma ray detection for determining elements on other planets in our solar system. Gamma rays are also produced within the sun when high-energy particles collide with material in the sun’s atmosphere. When cosmic rays strike the surface of the moon they blast apart atoms and molecules within the lunar surface. This also produces gamma rays.
Highly magnetized, spinning neutron stars — pulsars — produce powerful electrical fields, millions of times more powerful than lightning on earth. These fields create showers of high-energy particles that result in beams of radiation of wavelengths from radio waves through gamma rays. Some of these pulsars are found powering nebulas. M1, the Crab nebula, is powered by a fast rotating pulsar that sends out beacons of electromagnetic energy.
As amateur astronomers, we have few means at our disposal for examining the entire electromagnetic spectrum. We do, however, have at our disposal numerous references for studying the universe that is invisible to us. It is our curiosity and passion for astronomy that drives us toward a deeper understanding and appreciation of the celestial objects we view through our telescopes. By combining what we learn about the cosmos with what we see through our telescopes we can employ both our eyesight and the minds’ eye to really see the vast and incredible universe that unfolds before us every awakening day.
It is my hope that I have instilled in you a desire to eagerly venture into the cosmos with an insight that will permit you, from this day forward, to see the unseen, to see, as it were, the light. I am willing to wager that during your next stargazing session your combination of passion, curiosity and love for astronomy will have you seeing all of your subjects as you have never seen them before. That’s a horse I’m willing to bet on.
An AFSIG Article by Paul Trittenbach
This time of year always seems to carry with it a certain atmosphere. The holidays bring a dramatic change in people — both good and bad — along with the change in the weather. As a child, I remember this time of the year for all the holiday festivities and the specials that ran on television. One of my first experiences with a holiday story was the black and white movie version of Charles Dickens’, A Christmas Carol, starring Alastair Sim. This reverse version of Dr. Jekyll and Mr. Hyde, where Mr. Hyde turns back into Dr. Jekyll, was a stirring demonstration of two of the greatest human emotions: love and compassion! In the story a bitter old miser named Ebenezer Scrooge is transformed into a kindly and gentle soul after the visitation of the ghost of his former business partner, Jacob Marley, and three spirits who represent the ghosts of Christmas past, present and future.
As I sit here writing and listening to the music of Bob Marley (I don’t have any works by Jacob) I am reminded that I have to complete an article for December. Bob Marley may not be appropriate Christmas music but he does remind me of Jacob and that moving story by Charles Dickens. So here I am to haunt you with the forecast that this Christmas you will be visited by three spirits: the ghost of Stellar Past, Stellar Present and Stellar Future—all in one night. In their presence and enlightened by the knowledge of their workings I hope that you will be transformed into a new man. May the spirits move you and forever transform the way you see the universe.
Now that you have made it through the Thanksgiving holiday and are hoping that Santa is going to bring you a workout video, let’s start with a workout warm-up by lifting and toting that telescope. 1 and 2 and lift and carry and set up the tripod; 3 and 4; and collimate and…
There’s really nothing like a good workout to get the heart pumping and keep the joints flexible. But we are also going to workout our eyes and brains as we ponder the celestial objects overhead.
Wintertime brings on a great deal more than an opportunity to test your mettle against the frigid cold of the season. Darkness falls early this time of the year, so it’s easy to get outside and see many of the spectacular objects of December. In a single night, my neighborhood becomes haunted by the ghosts of stellar past, stellar present and stellar future. I’m no Scrooge! Every December, around Christmas, I pull my telescope out of the closet and set it up in front of my house to present the entire neighborhood with a Cosmos Carol. What could be a better and bigger gift than offering everyone the entire universe?
But I have a real star Party! I purchase bulk cookies, hot chocolate and coffee and have a microwave handy to warm the milk for the chocolate and a coffee marker for fresh coffee.What could possibly complement a good workout better than hot chocolate and cookies? I have a portable radio handy and put on some music to create ambiance for the evening. You can start the evening with appropriate stargazing music, such as the Planets by Holst or you may choose to create a compilation of astronomy related music. For me, music and stargazing goes hand-in-hand.
Ebenezer’s transformation from Mr. Hyde into Dr. Jekyll centers on a couple of supporting characters that include his clerk, Bob Cratchit and his entire family, and Ebenezer’s nephew and his family. Scrooge is visited by the spirit of Marley who informs him that he will be visited by the ghost of Christmas past, present and future to be shown the error of his ways and given another chance to make things right. As a reformed man, he wakes up to a new day — Christmas Day — with a brand-new heart.
Ebenezer had to wait until the clock struck 1 AM before he was able to start his journey to becoming a transformed man. You will be able to start your journey as soon as the sun goes down and your telescope is set up. Ebenezer’s journey to New Manville begins with a visit by the ghost of Christmas past, who shows him the pain and tragedy of all the things that Ebenezer missed — including lost love — during his youth. The universe is far kinder to us because light travels at a fixed rate of speed and we are able to journey into the past by simply pointing our telescopes anywhere. In essence, we haven’t missed anything from the stellar past. Nature offers up her secrets if we look far enough across the cosmic ocean. But the ghost of stellar past does reveal to us that there is pain and tragedy in the death throes of stars!
The Ghosts Of Stellar Past
Located 1500 light years from Earth in the sword of Orion’s belt is M42, the Great Orion Nebula. This combination reflection and emission nebula is the product of an enormous explosion of an old red giant millennia ago. When the fuel of that star was exhausted, its outer layers succumbed to gravity and collapsed into its core within a few seconds, until the atoms could no longer crowd together. With the explosive force of thousands of hydrogen bombs they were shot away at supersonic speeds into interstellar space.
The result is an expanding cloud of dust and gas that today occupies an area of 24 light years across by 50 light years high. As the cloud continued to expand outward at supersonic velocities the gases and dust crashed into one another further compressing them to form more complex molecules, including the organic molecules of living things. The death of the red giant mother that led to the creation of M42 also gave birth to new stars and nascent solar systems. Within M42 there are 700 known stars, 150 of which possess protoplanetary disks. These stars are at various ages of formation with the youngest and brightest members believed to be only 10,000 years old and the oldest no older than 300,000 years. Within dense cocoons of gas new protostars are
At the center of the nebula is a collection of four stars that form a trapezoidal shape known as the Trapezium. These four stars emit light in the ultraviolet region, exciting the surrounding gas and causing them to glow in the brilliant colors we see in images of the nebula. At the same time, the energy of the stars is carving a cavity within the nebula and causing many of the young stars to erode away. The nebula is both mother and cannibal!
Dark, cavernous areas within the nebula contain BOK globules. This is protostellar matter that will collapse under the forces of gravity to ignite as stars. In addition to the young, hot stars, the Hubble space telescope has spotted numerous black dwarfs within the nebula. These objects are too small to become stars and remain cold because they cannot sustain their cores way stars like our sun do. The Great Orion Nebula emits light predominately in the ionized oxygen region. You will find that an OIII filter will help you to pull out details of this stellar ghost.
M43 is a smaller nebula associated with the Great Orion Nebula and part of the entire structure known as the Orion complex. In images and shorter focal length eyepieces of our telescopes M43 seems to be attached to the Great Orion Nebula. It is also located 1500 light years from Earth in her prolific stellar nursery. Recent Hubble Space Telescope images have shown a lobe attached to M43 that is pushing back against the erosion caused by the ultraviolet radiation of the stars of M42.
Like a ghostly eye 2200 light-years away in the constellation Cygnus NGC 6826, the Blinking Planetary Nebula stares back at you through the telescope. This is a remnant of the star similar to our sun that grew to the red giant phase and then shed off its outer layers leaving a star of carbon and oxygen — a white dwarf — as a corpse. The gas layers expand into interstellar space and form a large bubble that emits light because it is excited by the ultraviolet radiation of the white dwarf at its center. Planetary nebulae result when low mass stars like our sun swell into a red giant phase at the end of their life. Instead of erupting in violent explosions, they shed their outer layers to create ghostly and beautiful clouds. Unfortunately, the white dwarf star that is left behind generates enough energy to quickly erode the nebula, and these types of nebulae have short periods of only about 10,000 years, as opposed to the billions of years of their parent stars.
Located 6500 light years away in the constellation Taurus is M1, the Crab Nebula. Like the Great Orion nebula, M1 is a supernova remnant, that has expanded to currently occupy a radius of 10 light years and is still expanding at a velocity of 1500 kilometers per second. Through the telescope M1 appears as an oval shaped mass of filaments. These filaments are the remains of the layers of the parent star’s atmosphere.
The beating heart of the Crab Nebula is a pulsar — a neutron star rotating at approximately 30 times per second. The pulsar is approximately 30 km across and emits radiation in x-ray wavelengths. This ionizes and excites the cloud of gas which is predominantly hydrogen and helium. The nebula is visible to telescopes with apertures as small as 4 inches but it glows at a magnitude of 9.0 and details of it can only best be experienced through a large aperture telescope. The pulsar beating at its heart is only visible through apertures of 20 inches or larger.
The supernova explosion that created M1 was witnessed by Chinese astronomers in 1054 A.D. It glowed so bright that it could be seen in the daytime and people could read by it at night for two months after the initial explosion. According to Chinese records M1 was the brightest object in the sky, next to the moon, and reached the magnitude of -7.0. It remained visible in the night sky for 653 days after its initial discovery.
The clock struck 2:00 and Ebenezer was awaken by the spirit of Christmas Present. Ebenezer was taken along the streets of the city and shown the tragedy of those who were less fortunate. He had walked among those streets every day and seen the suffering of the masses but he chose to remain blind to them and ignorant of the fact that if all men truly loved each other they could solve all human suffering. The second ghosts to visit us, the Ghosts of Stellar Present, will take us through the streets of our “star city,” the Milky Way, and show us some souls that burn brightly — in some cases upon other worlds. However, I caution you to not be complacent because even our star, the sun, could rear up an ugly head and deliver a storm that could one day leave us hoping for mercy. Humans may be cruel but nature has no concept of good and evil. Its cycle of destruction and creation are simply defined as “existence”.
Ghosts of Stellar Present
If you need to show a ghost of stellar present, you wouldn’t have to go any farther than your backyard. Our sun is an excellent example of a medium yellow star that burns brightly enough and long enough to sustain planets that harbor life. If you own a solar telescope or solar filter and you prefer to set up in the daytime, than the sun would be both an easy target and a well-known celestial object for presenting as a ghost of stellar present. But if you’re looking for a nighttime analog there are billions of type G stars in the Milky Way galaxy. First, we will start by talking about our sun. Regardless of any nighttime analog you may choose, the knowledge that you will glean about our sun will be applicable to understanding the stellar object.
Located approximately 93 million miles away is our star, the sun. The sun is the beating heart of our solar system and is in essence a hot, glowing ball of plasma with an influence that extends well beyond the orbit of Pluto. Without our sun there would be no heat or life here on earth. The gravity of the sun holds the entire solar system together. The sun generates an electrically charged magnetic field that is conducted throughout the solar system creating a stream of electrically charged gas — the solar wind — which travels through the solar system in all directions.
The sun’s interaction with our planets drive the ocean currents, weather, climate, our seasons, the radiation belt and the auroras. Although it is the only one we have, our sun is one of billions of yellow stars throughout the Milky Way. The sun and our entire solar system formed within a giant rotating cloud of gas and dust — a solar nebula — approximately 4.5 billion years ago. As gravity caused the nebula to collapse, it began to spin faster creating a flattened disk. Our sun was created when the bulk of the material, 99.8% of the mass of the solar system, was drawn to the center, and under the influence of gravity ignited to create our star.
Our sun is 1.3 million times the size of the earth! With a radius of 695,508 km and as much as 332,946 times the mass of the earth, our sun may seem like a very large star, but it is in fact an average star and there are many more that are several times larger. Different parts of the sun rotate at different velocities but at the equator the sun spins around approximately once every 25 days. At its poles, the sun spins around once every 36 days.
The sun’s mass, like all other celestial objects, is held together by gravity. The sun itself consists of six different regions: the core, the radiative zone, the convective zone, the photosphere (which is the visible region), the chromosphere and the corona. The temperature of the sun’s core is 27,000,000°F, a temperature that is hot enough to sustain thermonuclear fusion. At the core, atoms of hydrogen are fused (cemented together) to create helium and more complex elements.
The core creates energy to produce all the heat and light of the sun. The energy is radiated outward from the core into the radiative zone where it bounces around for 170,000 years until it can reach the top of the convective zone. In the convective zone the temperature drops to 3,500,000°F and large bubbles of hot plasma begin to migrate outward. Although the temperature of the surface of the sun is only 10,000°F it is still hot enough to create and boil carbon!
The photosphere is a 300 mile thick region from which most of the sun’s radiation escapes into space. In our eyes this radiation appears as sunlight and takes eight minutes to reach the earth. Above the photosphere is the chromosphere and the Corona, a tenuous, thin atmosphere. When we hear of or see solar flares and sunspots for ourselves, this is the area in which they occur. The light of this region is far dimmer than that of the photosphere and the only time that we are able to ever see it is during a solar eclipse. Ironically, the temperature in the sun’s atmosphere increases as the altitude increases — reaching as high as 3,500,000°F. The source of this heating is a scientific mystery.
The sun is a giant dynamo that generates a complex magnetic field that extends outward into interplanetary space. This region of influence is known as the heliosphere. A stream of electrically charged gas flowing from the sun carries the magnetic field into interstellar space. As the sun rotates, its magnetic field is churned outward in a giant rotating spiral.
The sun is not always a quiescent star friendly to life on earth. It goes through periods known as solar cycles, which occur approximately every 11 years. At that time the geographic poles of the sun change their polarity and the photosphere, chromosphere and corona transform from quiet and calm into violent. The height of this activity is known as the solar maximum. It is a time of sunspots, flares, solar storms and coronal mass ejections. They are the results of irregularities in the sun’s magnetic field and can release enormous amounts of energy and particles into space, some of which reach Earth. This space weather can damage satellites and affect the power grid, threatening the whole of civilization.
Forty light years away in the constellation Auriga is the giant double binary type G star, Capella (Alpha Aurigae). The two brightest stars of the system are type G, similar to our sun but about 10 times its diameter. The stars are orbited by smaller red binary companions. The two main stars are separated by only about 60 million miles, two-thirds the Sun-Earth distance and orbit each other every 100 days. Both the A and B stars are about 80 times as bright as our sun. Because of this, the system would be too hot to harbor complex life like that of Earth. Nevertheless, Capella is a good nighttime analog to our sun and a good choice for your nighttime viewing.
Capella A and B are both yellow-orange giant stars in a post-main-sequence phase. Both are older and many times larger than our sun. In this stage they have exhausted most of the hydrogen fuel at their cores and have expanded to five times their original size. Over the next few million years both stars will become red giants — a fate that will be shared by our sun in 5 billion years — and expand to hundreds of times their original size.
Capella A is the larger of the two stars with a radius 12 times that of our sun. Capella B as a radius of about nine times that of our sun. Both stars have masses and surface temperatures similar to Sol. Both stars are aged at around 500 million years old. Visually, Capella appears as a single star. A telescope resolves it into a type G binary, but the additional red dwarf binary companions will not resolve in amateur equipment.
Over the past few years red dwarf stars have come into light as astronomers have become more interested in them as possible targets for Earth-like planets. Red dwarf stars are much smaller than our sun and burn much cooler. But they also burn much longer and this combination opens the possibility to earth-like worlds occupying the Goldilocks zone in a proximity much closer to the star. Red dwarf stars also exist in a greater population than any other star type in the Milky Way galaxy.
Science fiction fans will remember that 40 Eridani A is the star of the fictional planet Vulcan, home to the first officer of the starship Enterprise, Mr. Spock. Unfortunately, no planet is known to exist around this star. Current technology is not up to the task of finding one. It has been calculated that a planet circling 40 Eridani A would be located at position of .68 AU away, 2/3 the sun-earth distance. The B and C stars would burn brightly in the Vulcan sky. Although both stars would be visible during the daytime their light would not be bright enough to completely negate the nighttime sky from the inhabitants of 40 Eridani A.
40 Eridanis C is a red dwarf star located 16.5 light years away in the constellation Eridanus. It is a member of a triple star system of Omicron Eridani composed of dwarf stars. The A star is a main sequence dwarf type G, similar to our sun but much smaller. 40 Eridani B is a white dwarf and 40 Eridani C is a red dwarf. The white dwarf B star would put out so much radiation that any planets circling it would be sterilized by its ultraviolet radiation. 40 Eridanis C flares with periodic increases in x-rays in addition to visible light. This, too, would prohibit the possibility of life developing on any planets orbiting this world. However, the star is an example of an M class dwarf and should be considered a good analog to Proxima Centauri B, our nearest neighbor which is now believed to harbor an Earth-like world.
Because of its close proximity to earth, 40 Eridani C is an easy telescopic target and another example of a Ghost of Stellar Present. Recently the news was buzzing with the announcement of the discovery of a small, possible earth-like planet circling our nearest neighbor, Proxima Centauri B. It appears that this planet resides in the Goldilocks zone of that red dwarf. When scientists talk about Earth-like worlds they are speaking of stars are in the right place – the right distance from their sun — to harbor liquid water. This doesn’t mean that the planet may contain complex life like our own. The search for life in the universe, at the present time, is a search for whatever life we may find. Most of this will probably be microbial similar to the single celled organisms we see on earth. Most of them will probably be extremophiles and thermophiles, organisms capable of existing in environments that would be hostile to us.
The existence of life on other worlds will certainly be a transformative experience for the human race. Given the abundance of organic molecules in the interstellar medium it seems highly unlikely that life doesn’t occur in many places throughout the universe. Scientists are even turning to the moons of Jupiter and Saturn to find primordial life. Even extinct life, contained in fossils on Mars and possibly our moon, could teach us a great deal about the chemistry of life and may help to solve the debate over whether life originated here or was transported to earth via comets.
In A Christmas Carol, Ebenezer’s transformation is completed by a visitation from the ghost of Christmas future. After Ebenezer witnesses the loneliness and sadness that he could have prevented during his lifetime he repents as he kneels at his own grave. In the story, Christmas Day is tomorrow and we are led to believe a Christmas future, the day upon which Ebenezer is resting in a lonely grave, may be tomorrow. In fact, for all he knows Ebenezer may already be dead and the ghost of Christmas future may be simply showing him events that he cannot prevent. After all, he does ask a non-responsive ghost of Christmas future if the events he has witnessed are things that will be or things that must be.
As soon as Ebenezer awakens to realize that he is still alive and the ghosts have delivered upon their promise to reveal all to him in one night, he is an elated man (on Messier cloud nine) who immediately sets about to his business — mankind! Now I don’t know about you, but if I were kept up all night I would not be as cheerful as Ebenezer — at least not before I’ve had a few hours sleep and an IV bag full of coffee. That even includes awakening on Christmas Day with the knowledge that under the tree was that workout DVD I so coveted!
The Ghosts of Stellar Future
We do not have to fear the ghosts of stellar future because that takes place billions of years from now. Eventually our own star will bloat into a super red giant, then shed off its outer layers and become a planetary nebula similar to the Ring nebula in the constellation Lyra. The universe itself may have already seen its greatest star forming phase. As dark energy propels all the atoms of the universe apart into an eternally inflating universe, the stars we see today will eventually fade from view until they themselves are flung apart by the forces of that energy. While A Christmas Carol may have a happy ending, a Cosmic Carol will have a cold and tragic one.
The ghosts of stellar future that will visit upon us will be the ghosts of the astronomical near future — billions of years from now. We can see many of the spirits roaming our own Milky Way galaxy today, old stars that have grown into the monsters of the present. They are examples of stars of the future — stars like our sun and many of the others currently inhabiting our galaxy and the rest of the universe.
If there is an outstanding of the ghost of stellar future in December’s sky it would have to be Betelgeuse in the constellation Orion. Designated as Alpha Orionis, Betelgeuse is one of the brightest stars in the winter sky and part of the winter triangle. Betelgeuse is a super red giant near the end of its life cycle. If Betelgeuse was located at the center of our solar system its surface would extend beyond our asteroid belt, consuming all the inner planets out to Mars. It is located 640 light years away in the shoulder of the constellation Orion. When Betelgeuse dies it will produce an enormous supernova explosion, sometime within the next million years.
Like the star Mira in the Constellation Cetus, Betelgeuse is a runaway star plowing through interstellar space at 30 kilometers per second and leaving a bow shock in its wake. It is also classified as a semi-irregular variable star with periods of variability from 400 to 2100 days. Betelgeuse possesses at least 20-30 times the mass of our sun and 2 million times its volume. It shines 100,000 as brightly as our sun. High mass stars such as Betelgeuse exhaust their fuel very quickly, existing for only a few million years, as opposed to our sun which will live for billions of years. Betelgeuse is aged at 10 million years and is already nearing the end of its lifespan!
Stars at least five times the mass of our sun can grow into super red giants at the end of their life cycle and go out in a grand supernova explosion that results in either a nebula, similar to the Great Orion nebula, a neutron star or a black hole. The fate of Betelgeuse is likely to be another nebula similar to that of the Great Orion Nebula (M 42).
Stars 1.5 to 3 times the mass of our sun grow into red supergiants, die in a supernova explosion and leave a neutron star, while other, more massive stars can go on to produce a nebula or black hole. All of that depends upon their mass and how their atoms recombine in the final moments of their lives. Stars 15 times the mass of the sun may continue to contract to form a singularity—a black hole.Because of its mass Betelgeuse likely to become a neutron star. Neutron stars occur when the core of the star is compressed tightly and the electrons are stripped off from the atoms. The result is a large ball of nuclear material — matter of the atomic nucleus — the size of a city, such as New York or Paris. Consider an object twice the size of our sun compressed down into a city-sized object. The core is so dense and the gravity is so enormous that a single teaspoon of neutron star would weigh billions of tons!
Because of its density the gravity of a neutron star is so immense that to escape it you have to have a velocity of half the speed of light. A mountain on the surface of a the star would only be millimeters high. Light traveling around such a star would be gravitationally lensed, so astronomers would be able to see things behind a neutron star. A neutron star would compact 500,000 times the mass of the earth into a sphere of only 12.4 miles.
As the core of the star continues to collapse inward, its rotation increases in it can spin up to thousands of times per minute. These rapidly rotating stars are known as pulsars. They can emit beacons of light that can be picked up in the x-ray and radio spectrum. When viewed from Earth these pulsars resemble the beacon of a lighthouse. As material from the pulsar accelerates within its magnetosphere it produces gamma rays, which can slow the pulsar down. If the beam from a pulsar does not flash in the direction of earth, cannot be seen. All pulsars are neutron stars but not all neutron stars are pulsars.
Magnetars are neutron stars that have magnetic fields thousands of times stronger than the average neutron star. The drag of the magnetic field slows the star down so it takes much longer to rotate than a pulsar. Magnetic fields can be so strong that they will distort the shapes of atoms! A fracturing of the surface of a magnetar can release a large pulse of radiation that can be detected up to tens of thousands of light-years away. This release of radiation is known as a starquake. Magnetars can remain active for 10,000 years, after which the magnetic field is fully dissipated and the star cools down.
Sometimes neutron stars will collide and create a black hole. This process takes milliseconds to
occur. The rapidly rotating black hole created from the two neutron stars spins so fast that it emits jets of material that travel light years back into space. Images of these “quasars” have been seen at the centers of galaxies where supermassive black holes are rapidly spinning and digesting orbiting stars! In their gluttonous feeding, however, enormous amounts of material are ejected from the poles of the black hole into interstellar space. These are the jets that we see in images of quasars. Colliding neutron stars produce gravitational waves that can be detected with devices such as the LIGO detectors here in the United States.
What a piece of work is a man! How noble in reason, how infinite in faculty! In form and moving how express and admirable! In action how like an Angel! In apprehension how like a god!
Hamlet, Act 2, scene 2
Oh, if William Shakespeare had only been an astronomer! He might have written about what a piece of work the universe is. How elegant in its construction and workings, how infinite in breadth! How moving in mystery and intrigue! How secretive and yet willing to share her secrets! To look into her eyes is to look into a mirror and see yourself!
Call me Ishmael (my name is actually Paul). Whenever a balmy November wind blows across my bow and chills me to the bone, when the brisk November air suggests that autumn is turning to winter, when the skies of night become calm and tranquil and abound with good astronomical seeing, and whenever I find my heart longing for a dark observing site, I account it is high time to set sail into the infinite seas of the cosmos.
Pseudo Melville, The Great Whale
An AFSIG Article by: Paul Trittenbach
Moby Dick is probably the most infamous manuscript of Herman Melville. Scholars may disagree that it was his best work, but the novel does touch the soul of any reader. Moby Dick is fraught with emotional and philosophical undercurrents that leaves an indelible mark upon those who voyage through it pages. Melville inspired me when I found my thoughts turning to create a web article for November. Both Moby Dick and my composition have something in common—a great whale!
The Constellation Cetus, the whale, swims in the 13.8 billion light year ocean of our universe among other constellations associated with water: Eridanus, Aquarius and Pisces. In Greek mythology Cetus was known as “the sea monster” from the myth of the princess Andromeda. According to the myth, Andromeda’s boastful mother, Cassiopeia, angered Poseidon (the god of the sea) and the Nereids (nymphs of the sea), by claiming that she was more beautiful than they. Poseidon sent Cetus to punish King Cepheus and his wife Cassiopeia for the boast, requiring that they sacrifice their daughter to the sea monster or have it ravage their land.
King Cepheus and his wife chained their daughter to a rock so the sea monster could devour her. But just as the sea monster was about the partake of this delicacy, our hero Perseus entered the picture and killed Cetus, rescuing Andromeda from her fate. Later the two were married.
Cetus sits high in the southern sky and is prime for hunting by mid month. It possesses two red giants, one a pulsating variable—which is also a binary system— an orange giant and one G-type star smaller than our sun. It has 14 stars with planets and covers 1231 square degrees of space. There are three meteor showers associated with Cetus: the Omicron Cetids, October Cetids and Eta Cetids. The constellation is also home to nine galaxies available to amateur astronomers.
Unlike Capt. Ahab, I am unwilling to chase this whale around any maelstroms or round Perdition’s flames. I just sit patiently and wait until the earth transits around the sun and the overhead sky turns to the stars of autumn. Then Cetus presents itself overhead. There are plenty of other celestial objects to keep me occupied in the meantime. But when Cetus appears overhead it offers cosmic gems worth harpooning. In pursuit of our quarry, let’s first turn toward the stars of Cetus.
“…the great floodgates of the wonder-world swung open…”
Herman Melville, Moby Dick, or The Whale
Regardless of what aperture you choose you will never see Alpha Ceti V, the planet to which the genetically superior Kahn and his band of rebels was exiled by Capt. Kirk in Star Trek, the Original Series, after attempting to commandeer his ship. Made famous by the episode “Space Seed” and revisited in the motion picture Star Trek II, “The Wrath of Kahn”, Alpha Ceti (Menkar) has been deceptively hiding her planets. Of all the extrasolar planets discovered thus far none have ever been found around this star.
Designated as the alpha star, Alpha Ceti is actually the second brightest star in the constellation. Located 249 light years away, at magnitude 2.5 Menkar is a red giant with more than twice the mass and 89 times the radius of the sun. When it dies it will shed its outer layers and evolve into a planetary nebula, a fate that our sun will share in 5 billion years. Some people believe that Menkar is designated the Alpha Star because it sits close to the plane of the ecliptic and marks the path of the sun across the sky. In Arabic Menkar means nostril. The star sits at the head of Cetus.
Deneb Kaitos—Beta Ceti— is the brightest star in Cetus. It is located 96.3 light years away and shines at a magnitude of 2.04. Deneb Kaitos is an orange giant possessing 2.8 times the mass and 16.8 times radius of the sun. Deneb Kaitos has evolved from a main sequence star and is on its way toward becoming a red giant.
Plowing its way through interstellar space at 291,000 miles/sec the variable star Mira (Omicron Ceti) creates a bow shock and leaves a 13 light-year long tail of dust and gas in its wake. That light is visible only in the ultraviolet frequencies, and was detected only recently by NASA’s Galaxy Evolution Explorer telescope. Mira is a red giant star close to the end of its life. Mira has already ejected enough mass into surrounding space to create 3,000 planets the size of our home.
When it dies it will shed off its outer layers and become a planetary nebula. Mira is also a binary system. The B star (Mira B) is a white dwarf that is accreting mass from the primary. Images taken by the Chandra X-ray Observatory show that matter from the primary star is being consumed by the white dwarf. Both stars are separated by a distance of 70 astronomical units.
Mira is a pulsating variable star—the first of its kind to be observed—and is now part of a class of pulsating variables known as Mira variables (M Variables). All of the stars in this class, 6 – 7000 of them, are red giants that pulsate with varying periods of brightness of between 80 to 1000 days. Mira has a period of 332 days and can vary in brightness from magnitude 2.0-10. Mira is located 420 light years from Earth.
Of all the likely candidates, you would think the Star Trek writers would have chosen for a place to maroon Kahn and his band of genetic supermen, you would think it would have been Tau Ceti. Tau Ceti is a yellow dwarf star 11.9 light years distant that shines at magnitude 3.5. Is one of a few G-type stars that possesses less mass and brightness than our sun. In 1960 it was chosen by Frank Drake as one of the original Project SETI (Project Ozma ) candidates to search for intelligent life in the universe.
At millions of light years distant, galaxies are like great white whales swimming in our ocean universe. In binocular’s and small telescopes they shine as nothing more than milky clouds on the dark backdrop of space. It is difficult for us to wrap our minds around the great distances of the cosmos. Even members of our celestial neighborhood are trillions of miles away — far beyond our reach by any means of the rules of the Einsteinian universe.
Compared to the distances in our cosmic neighborhood, these great white whales are immense! But even the distances between them and the expanse of the universe itself makes them seem like amoebas in a drop of water! So here we are, Jonahs in the belly of a great white whale, staring out into the ocean with intense curiosity.
45 million light years away is Messier 77 (M 77, NGC 1068) a barred spiral galaxy at magnitude 9.6. It is one of the largest galaxies listed in the Messier catalog and the only Messier object in Cetus. It spans 170,000 light years in diameter and is the closest and brightest of the Seifert galaxies. These are galaxies that possess hot, highly ionized gases which emit intense radiation and glow very brightly. This radiation is caused by a very Active Galactic Nucleus (AGN) — a black hole — about 15 million times the mass of our sun! M77 also has very bright arms, the result of prolific star formation.
Located 250 million light years away is the spiral galaxy NGC 17. You will need a large aperture telescope to see this galaxy; it possesses a magnitude of 15.3. NGC 17 is believed to be a merger between two larger disk galaxies because it demonstrates prolific starburst activity and its core is still very rich in gases.
The barred spiral galaxy NGC 45 shines at approximately a magnitude of 10.4 and is located 32.6 million light years away. You will want to use a large aperture telescope to wrestle any details from this galaxy. Although it is very large, the surface details of NGC 45 are spread out and faint. This galaxy presents itself in a nearly face-on orientation to our plane of view.
At 236 million light years away the barred spiral galaxy NGC 47 shines at magnitude 13.5. Like NGC 17 and NGC 45 you will want to use a large aperture telescope to tease out any details from this galaxy. NGC 47 is a small galaxy with a very bright core.
Much closer to us, at 11.1 million light years is NGC 247, also known as Caldwell 62. NGC 247 is a small spiral galaxy— also classified as a dwarf spiral galaxy— and one of the closest to the Milky Way. It is a member of the Sculptor group of galaxies. NGC 247 possesses a bright nucleus surrounded by stars, gas and dust. The gas forms bright knots in the HII regions that are scattered throughout the galaxy’s outer arm.
Images taken by the Hubble space telescope show that NGC 247 has a large void in the HII regions, which spans nearly 1/3 of the length of the galaxy. Stars in this void are old, red and faint, and indicate that star formation has been halted in this region. It is believed the star formation in this region has not taken place in at least 1 billion years!
At 60 million light years distance the face-on spiral galaxy NGC 1042 shines at magnitude 11.0. It is typically associated with a nearby galaxy NGC 1035 and believed to be gravitationally bound to it because both demonstrate a similar red shift. NGC 1042 possesses a very bright Active Galactic Nucleus (AGN).
Located 60 million light years away, NGC 1055 is the dominant member of a group of small galaxies which are part of the NGC 77 galaxy group. Viewed from our position, NGC 1055 is an edge-on galaxy approximately 100,000 light years across. This galaxy possesses a large box-shaped halo that extends far above and below the galactic plane. In appearance, it bears some resemblance to the Sombrero Galaxy, NGC 104.
NASA images show faint structures within the galactic halo that are believed to be remnants of an interaction with a larger spiral that took place 10 billion years ago. Like NGC 77, NGC 1055 is a prolific star producer. NGC 1055 shines at magnitude 11.4 and will require a large aperture to be able to discern its structure.
NGC 1073 is a barred spiral galaxy similar to our own Milky Way that possesses a very active nucleus that glows in the HII region. It is 80,000 light years across and 55 million light years away. Hubble space telescope images show visible dark dust lanes, glowing in the HII region, young clusters of blue stars and an active nucleus which likely contains a black hole. NGC 1073 shines at a magnitude of 11.5 so you will want a large aperture to view this galaxy.
NGC 1087 is 80 million light years distant and 86,800 light years in diameter. You will want a large aperture to capture this galaxy. It shines at magnitude 12.2. It is classified as an intermediate spiral galaxy, possessing a small central bar of irregular features surrounding a disk. The overall surface brightness of the galaxy is very low.
Oh, Starbucks (Espresso, Frappuccino, iced coffee or dark roast)! Stand fast by my side. For I stand duty watch on the Forecastle and man the spyglass!
Pseudo Melville, The Great Whale
When the cold November wind blows across your bow and the nights become tranquil and accompanied by good astronomical seeing, I hope that your heart will yearn to shove off to a remote dark location and set sail into the infinite seas of the cosmos. There is a diamond mine out there, among the stars—filled with cosmic gems.
An AFSIG Article by: Paul Trittenbach
Under the darkness of a new moon sky on October 31 ghosts and demons will arise from the netherworld and walk upon the earth. This is the day of Samhain (pronounced “Sah-win”), summer’s end, a 2000-year-old Pre-Christian Celtic celebration held around November 1 for the ending of summer and the time of harvest. Some historical legends purport that the Celts lit bon fires and donned costumes to ward off the dead. In the eighth century Pope Gregory III declared November 1 All Saints Day and incorporated some of the Celtic celebration into the Christian.
Perhaps when humans invented religion we had a need to explain the good and evil we saw in each other, so we balanced the equation by creating the good gods above and the evil ones below. It is a theme that has permeated our literature and movies and has been handed down since the first spoken languages have appeared in our species. And throughout our history almost every culture has celebrated the dead in one way or another. All Hallows Eve was the evening before All Saints Day and later evolved into the modern day celebration of Halloween.
Modern-day Halloween is a playful way of dealing with death. It is a time when little goblins of the neighborhood come out to invade the night seeking treats and promising nasty little tricks to those who fail to deliver. To me, this night when the moon is dark is a great opportunity to dispel some of those demons with science. I propose that you offer them a treat they seldom if ever have experienced: a star party. It is an opportunity for fun suffused with education.
We begin our tour of celestial eye candy by introducing the pralines of the northern hemisphere: the double cluster of the constellation Perseus. NGC 869 and 884 lie 7,500 light years away. Star clusters are groups of stars that are gravitationally bound to each other and moving independently of the rest of the galaxy. The Perseus Double Cluster are the only two known clusters in the Milky Way that are gravitationally bound to each other and moving as a single component at 39 km/s (24mi/s) in our direction.
Each cluster consists of 300 known members of young blue-white stars 12.8 million years old. At the time when the light left these clusters to appear in the eyepiece of your telescope the first established human civilization was firmly planted between the Tigris and Euphrates rivers in the ancient land of Mesopotamia — it is today called Iraq. These were the Samarians, from which we have derived our modern-day word of summer. To them, as to us, the double cluster appears as a large, somewhat milky patch in the sky overhead and can easily be seen from a dark location.
This pair of open clusters is a stunning example of the treats available to amateur astronomers. I tell guests at public star parties that when they see these sparkling diamonds against the velvet black of space they will ask themselves why they never got involved in this hobby sooner. There are numerous other open clusters that you can compare against the Perseus Double Cluster; M38, 39, 34, 11 and the most infamous: M45, the Pleiades.
In contrast to the aforementioned open clusters are the globular clusters, such as M13. If the double cluster is the pralines of celestial eye candy then globular clusters must be the gumdrops.Turning to the globular’s immediately after showing the open clusters yields a stunning, “wow” moment for the audience. In addition to the visual impact of viewing the two types of clusters, both possess opposite historical and compositional backgrounds.
Globular clusters reside at the opposite end of the age spectrum. They are fossils of the cosmos nearly as old as the universe itself. M13 is 11.65 billion years old! Unlike open clusters which formed inside our Milky Way, globular clusters are nomads roaming the universe and temporarily taking up residence inside the halo of our galaxy. They are densely packed associations of stars — the proverbial Guinness book example of “how many people can you fit into a phone booth”.
On the evening of October 31 M13 will be in the western part of the sky, just above the horizon. This is the most densely packed globular cluster available to most of the northern hemisphere (Tucson, Arizona lies close enough to the southern hemisphere to catch a view of the Omega Centauri cluster). M13 consists of 300,000 known stars compacted into a spherical volume of 145 ly! In addition to explaining what a light year is in terms of distance, M13 is an exercise in warping the mind around celestial mechanics.
You can compare the distance between Earth and its nearest stellar neighbor, Proxima Centauri at 4.2 light years, away to the same spherical area at the center of M13. In the 4.2 light year distance between us and our nearest our neighbor M13 would have 100 stars! In the same spherical distance of 4.2 light years the core of M13 would be the residence of 1000 stars! You can point out that the known members of a star cluster are those that we are able to visually count and that the Milky Way is dominated by binary stars in addition to other star systems that consist of three or more members circling either one another or a common invisible axis.
At the time when the Kerbarian cave Culture of Haifa, modern day Israel, was being established the light from M13 was departing to arrive in your eyepiece. While those people were fabricating stone tools light from 300,000 stars shone brightly into the universe. M13 is located 22,200 miles away in the constellation of Hercules. It is a popular summertime object among amateur astronomers. From a dark site it appears as a small fuzzy patch and is easily viewed through a pair of binoculars or a small telescope. Telescopes, however, will resolve the patch into stars.
M2 and M15 both provide good examples of globular star clusters. M2 is probably easier to present from an urban area because of its magnitude of 6.4. At one time star clusters were grouped with the species of nebulae — murky patches of light scattered among the stars. The word nebula is ancient Greek for “cloud” and before the invention of telescope star clusters, galaxies and true nebulas were all cloud-like structures in appearance. Even into the early 20th century the Andromeda galaxy was known as the Andromeda nebula.
Now that you’ve demonstrated the magic of star clusters try pulling a binary star out of your hat. The constellation Cygnus, the Swan, hangs west of Zenith in October. Beta Cygni, otherwise known as Albireo appears as a single star to the unaided eye. However, it presents one of the most stunning binaries in the Milky Way galaxy. Albireo is also a test in color perception. One star is a cool orange while the other one is a hot blue. To my eyes, the primary appears as a golden yellow and the secondary is a hot blue. Together the two stars present a striking color contrast.
Alberio is located 380 ly (Light years) from Earth. Harvard University was being established when the light left Albireo to arrive In your eyepiece. The first and second component orbit each other with a period of 75,000 years. Two thirds of the stars in the Milky Way are binaries but few of them can boast the visual impact of Albireo. In addition to showing Albireo you may want to show the most common Milky Way binary, Polaris.
If you’re in the mood for telling ghost stories then nothing can be more appropriate than showing them a nebula. The best of the summer nebulae, the Trifid, Lagoon and Eagle lay low on the horizon. Those who have a good view of the southern sky may still be able to catch a fleeting glimpse of them. But there are other ghosts in the sky that we can turn our telescopes to.
Aside from most of the planetary’s, reflection and emission nebulae appear as ghostly apparitions of black and white clouds hanging in space. M27, the Dumbbell nebula, is one exception. From our viewing angle the dumbbell not only appears dumbbell-shaped, because of the way that its lobes have expanded from the white dwarf driving it, but it also appears black-and-white to our eyes. Located 1200 away these expanding clouds of gas have been blown from a star similar to our sun 4000 years ago. At the time of this star’s death the Babylonians were developing mathematics.
The outburst of expanding gas lobes witnessed on M27 are one light year across and expanding outward at a velocity of 20 mi./s. The Dumbbell nebula was the first Planetary Nebula (PN) ever discovered. An Ultra High Contrast filter (UHC) will help you to pull out the details of the Dumbbell. An additional nebula to look for would be the North America nebula. For additional details on the North American nebula see my Cosmic Gems article from August.
For a nebula of a different color try M57, the Ring nebula. At the time when the light left this nebula 2300 years ago King Ptolemy II of Egypt was only a few years away from building the very first lighthouse at the mouth of the Nile. It would be 400 feet high and seen from 40 miles away. But the Ring nebula is a more substantial lighthouse, with the light being pumped out by a remnant of a star of similar mass to our sun, which upon exhausting its hydrogen fuel shed its outer layers in the last, great gasp of death. The remnant of the star is a white dwarf no larger than our earth.
Viewed from our position the outward expanding shell of gas and dust are excited by the ultraviolet radiation emitted by the white dwarf and radiating a rainbow of colors. Although M57 is also a planetary nebula it is a colorful contrast to that of M27. The nebula’s expanding shell of gas is 1.3 light years in diameter. Nebulae provide an opportunity to discuss how chemicals are formed within stars and the explosions that occur after their death. It is also an opportunity to explain how new stars are formed along with any planets or life that may occur on them.
You gotta have monsters! No Halloween story would be complete without them. So now we turn to the Alpha Star of the Constellation Taurus: Aldebaran. Aldebaran, the eye of the bull, is an orange giant star located 65 ly away. When the light left the star Ethel and Julius Rosenberg were being convicted of selling A-bomb secrets to the Soviet Union by the United States.
Aldebaran is a variable star but his variability is virtually unnoticeable to the human eye. It is also a binary star, possessing a secondary that is only three light seconds away (as opposed to our sun which is eight light minutes away).At 43 times the radius of our sun ( the radius of our sun is 432,000 miles) Aldebaran is a monster, although far from being the largest star known. The largest star on record is VY Canis Majoris, a red hyper giant and a eighth magnitude star 1420 times the radius of our sun!
Of course if you really want to talk about monsters point to the area of Cygnus X1. You will not be able to show them this black hole through your telescope but you can tell them that it was the first confirmed radio source verified as a black hole. Black holes like Cygnus X1 are the Frankenstein’s of nature. Cygnus X1 is considered to be a stellar mass black hole possessing 14.8 times the mass of our sun. It is located 6,070 ly from Earth.
Periodically stars many times the mass of our sun exhaust their fuel and the remaining material loses his outward push against the attraction of gravity. The mass of the star is so great that the gravitational attraction overwhelms all existing matter which collapses inward to an point known as a singularity — a word that means “mystery”. So powerful is the attraction of gravity that nothing can escape it, even light itself. As a result, black holes are mysterious in nature, having yielded up clues only from stars around them — some of them they are cannibalizing.
The nearby star orbiting Cygnus X1 is HDE226868 a ninth magnitude O-type supergiant star. You should be able to locate this star through your telescope. Here is an opportunity to explain the invisible electromagnetic spectrum and the x-ray radio source that makes detecting a black hole possible. It’s also a chance to discuss the radio spectrum and how humans use it in our modern world.
Physicists and mathematicians have determined that the space and time near black holes is radically changed from the Newtonian laws of the universe. As a result, black holes have become a favorite subject of science fiction — including Star Trek where the Enterprise frequently utilizes them to travel back in time. Studies indicate that black holes are quite abundant throughout the universe. In fact, it is an irony that black holes seem to be destructors of stars and also the creators of galaxies.
The last object that I want to cover in my Halloween star party is M31, the Andromeda galaxy (Andromeda nebula). The Andromeda galaxy is a large spiral galaxy, like our Milky Way, except possessing twice the mass. Andromeda has 1 trillion stars and is the largest galaxy in our local group, a group of 45 galaxies, which constitutes part of a super cluster of 2000 galaxies known as the Virgo Super Cluster. It is approximately 220,000 ly across (the Milky Way is 190 ly across) and 2.5 million ly from Earth. At the time when the light first left the Andromeda galaxy to appear in your eyepiece humans were fashioning their very first tools.
M31 is our nearest galactic neighbor. It is on a collision course with our galaxy, which will take place in 3.75 billion years. It is visible to the naked eye as a large fuzzy patch in the constellation of Andromeda. It is visible through pair binoculars and easily viewed through low power in a telescope. The nucleus of Andromeda is so bright that overwhelms the eye of the observer Tell your guests that to get a good view they should use adverted vision — turn their eyes slightly off center of the galaxy to see the details.
I think a themed star party like one for Halloween would be a great way to have fun while providing education and sharing a fascinating hobby. I can envision some of you dressed up as Darth Vader and turning the little goblins of your neighborhood toward dark side of day. A star party like this would be a great team builder for your organization — with opportunities for a variety of topics, from mythology to science, history and science fiction, art and culture. It’s an chance to demonstrate how we’ve come a long way from how the ancients thought about the universe to science casting light upon the truth.
Of course a Halloween star party is about serving celestial eye candy. But it would be a nasty trick to forget the confectionery treats. Halloween is a costume party, and not just one for the youngsters, with sugary rewards. Perhaps in 4 million years when Andromeda merges with our galaxy we will have a new name for candy bar. For now, we still have the old standbys that we grew up with: Three Musketeers, Snickers, Baby Ruth, Kit Kat… — to share with the younger generations. But for now and into the foreseeable future, remember, you can’t star gaze without the Milky Way!
Searching for diamonds in the celestial haystack
An AFSIG article by Paul Trittenbach
Sailing for the new world
On August 3, 1492 Columbus set sail into the Western Atlantic and the unknown. He was seeking a short trade route to the East Indies, the land of spices, the gold standard of the time. At 2 AM on the morning of October 12 a lookout on the Pinta sighted land. Columbus had not reached the Americas however, in fact he never made landfall on North America. Instead, on that first voyage his ships made landfall on an island that he named San Salvador, believed to be one of the Cays in the Bahamas.
During his voyages of 1499-1500 Amerigo Vespucci made landfall in the South American continent, in an area of French Guyana then the mouth of the Amazon River. Vespucci was credited with discovering the American continent and both North and South America became named in his honor. Neither he nor Columbus had actually discovered the New World. Many others had come before them, including the Vikings. But no one can discount the enormous contributions that their explorations have added to history and how they have changed the world.
You and I stand on the North American continent, gazing up, awestruck by the cosmos overhead. We may not be explorers and discoverers but we are in our own right as we stargaze with our unaided eyes, binoculars, telescopes and through the various sources of media that help us to make discoveries of our own. And unlike the world’s great discoverers, we can do it in relative comfort, even in the frigid temperatures of winter.
On August 3, 2016 the moon will be waking up from its new moon slumber and showing us a thin sliver of itself. This seems to be an appropriate time to set sail for the cosmic shores of the North America Nebula (NGC 7000). The discovery of this faint emission nebula is attributed to William Herschel on October 24, 1786. But like the rest of history, it to may have first been landed upon—for all we know—by the Vikings.
The North America Nebula is a great expanse of stellar remnant that covers an area of 50 light years high by 40 light years across — covering an area of sky four times the diameter of the full moons! The North America Nebula lies about 3° off the port bow of Deneb, the brightest star in the constellation Cygnus. It is a faint patch of light, although some sources indicate that it is easily visible to the unaided eye in a very dark location. The nebula lives up to its namesake forming the outline of North America, Mexico and Central America. It is closely associated with a second patch of nebulosity — the Pelican Nebula (IC 5070). The two are separated by a dark lane of dust. Both are located 1800 light years distant and considered to be part of the same supernova remnant.
A star at least 10 times the mass of our sun reaches the end of its lifecycle and grows into a super red giant. In matter of a few seconds it expends the full amount of hydrogen of our sun — 10 billion years worth! The remaining matter loses its tug-of-war with gravity and collapses inward, producing heavier elements along the way. Finally, a devastating explosion blows the matter into interstellar space at 20,000,000 miles per second, leaving a sphere of oxygen and carbon the size of our earth — a white dwarf. A supernova is born.
The matter from this conflagration becomes an enormous interstellar molecular cloud, covering a volume of space that spans light years. It consists of complex chemical elements and compounds — including the gold in your jewelry and the organic compounds of your body. But nature is a great recycling machine and this material will not go to waste. Supersonic shockwaves, gravity and pressure will fabricate new stars and possibly planets and life itself. These cosmic stellar remains are a nebula.
NGC 7000 glows red in images, due to the ionized hydrogen that composes the cloud. The white dwarf embedded somewhere within the nebula emits ultraviolet light — an energy source so powerful that it can eject electrons from the hydrogen atoms and recombine them with protons in other atoms to emit light in the Hydrogen-alpha wavelength. An H-alpha or UHC filter should help you to see the nebula in greater detail.
Edwin Hubble originally suggested that the power source for NGC 7000’s cloud was Alpha Cygni —Deneb. Spectral analysis, however, dethroned Deneb. Other astronomers inferred that the star HD 199579 was the culprit. However, some debate exists around that star possessing the right spectral emissions to excite the hydrogen cloud.
The nebula is also a star producing region whose residents include two open star clusters: Collinder 428 and NGC 6997. NGC 6997 is the most obvious of the two star clusters and is located along the East Coast of North America. Collinder 428 resides in the location of the state of Washington. Along the western edge of Mexico and Central America is a bright wall, a star forming region known as the Cygnus Wall. This region is both lit and simultaneously eroded by young stars that are partially concealed by the dark dust lanes they have created. The Cygnus Wall spans a distance of 15 light years!
The associated Pelican Nebula, IC 5070, is an amalgamation of three structures (IC 5067, IC 5068 and IC 5070) collectively classified as IC 5070. This too is a churning molecular cloud of gas and dust, as evidenced in Hubble images, constructing new stars within. Because it is part of the same structure as NGC 7000 it glows red in images too. The two structures — NGC 7000 and IC 5070 — are separated by a dark dust lane, perhaps our analog of the Atlantic Ocean.
Once you have sailed the coastline of the North America Nebula and explored its interior, hoist your mainsail to shove off for the right wing tip of Cygnus. 4° south of Epsilon Cygni we find ourselves adrift in the Sargasso Sea of the Veil Nebula. Early mariners were petrified at the thought of becoming entombed in this expanse of seaweed desert in the Atlantic but we will be pleased to be lost here for some time. This large, filamentous patch of nebulosity is a part of a larger structure known collectively as the Cygnus Loop. The Veil Nebula, Caldwell 34, is a complex of multiple structures — including NGC 6960, Caldwell 33 (the Eastern Veil), NGC 6992, NGC 6995, NGC 6974, NGC 6979 and IC 1340.
The Veil Nebula is the remnant of a supermassive star that exploded about 8000 years ago. It’s name is derived from the filamentous structures that compose it. It is located approximately 2100 light years away and spans an area of sky of 110 light years. Because the nebula is spread over a very large area it appears very dim, regardless of the fact that it has a relative magnitude of 7. its filamentous appearance is attributed to shockwaves that are so thin that the shell is only visible when viewed edge-on.
High velocity shockwaves from the ancient explosion are plowing into a wall of cool, dense interstellar gas, causing it to omit the light of the nebula. At one time the star that created this nebula was more than 20 times the mass of our sun! The Veil Nebula glows from doubly ionized oxygen. It can be best viewed using an 0 III filter.
Hubble Space Telescope (HST) close-up images of the Veil Nebula reveals a bubble of gas that was blasted into interstellar space when its parent star detonated eight millennia ago. In the multi-spectral images it looks organic in appearance; an enormous transparent worm revealing its inner anatomical structures. Perhaps I am waxing romantic but it seems appropriate, with nebulas possessing organic compounds, to imagine it as more than a construct of pure physics. Images like this reveal so much more of the structure of these cosmic gems, enlightening us of the complexity and elegance of the cosmos.
To our eyes the gossamer structure of the Veil Nebula, matted against the jet black sky of interstellar space, is beautiful. It’s hard for us to imagine it as evidence of an immense nuclear bomb that detonated in our celestial neighborhood and was witnessed by ancient people. Perhaps in the cuneiform of the Sumerians or the oral stories of ancient American Indians there may be an eyewitness account of the event. Maybe one day we will uncover an edition of the Mesopotamian Daily Herald and read of one of the biggest news events of that time.
Having navigated the Veil Nebula we now set a compass heading 2.5° northeast of the double star Albiero and to the shores of Sharpless 2-91.To see this supernova remnant you will need a large aperture telescope.Use an OIII filter to view Sharpless 2 – 91. Sh 2 – 91 is a composite of tendril structures: Sh 2-91,Sh 2 – 94 and Sh 2 – 96. It is the shell of a star that exploded 20,000 years ago. This shell is 70 parsecs across and 2500 light years distant.
But Ahoy there, matey, we’re not through yet! After navigating the waters of Sh 2-91steer a compass heading 180° aft of Albiero and straight-on-through to the left wing of the Swan. The Swan swims along an enormous tear in the fabric of the Milky Way: the Great Rift. This is a lane of dark nebulosity that runs through the entire ribbon of the center of our galaxy. One point off our starboard bow we sight an orbicular dark cloud between Sadir and Deneb. This is a portion of the Great Rift known as the Northern Coalsack.
The Coalsack — that is to true Coalsack — is located in the southern constellation of Crux, 600 light years away from Earth. Whenever ancient mariners ventured into the southern seas and spied the Coalsack they shuddered in fear, for they believed it possessed properties of the occult. It is easy to understand how they must have felt; for it appears as a bottomless cavern amongst the stars. Our myths and religion are a bastion of hope pitted against our greatest fear of darkness and the unknown. Both the northern and southern coalsacks are icons of the primal impulses that can drive us mad with fear.
The Northern Coalsack spans an area of sky in northeastern Cygnus of 6° by 5°. It is the beginning of a long expanse of dark dust and gas that obscures and even conceals the stars behind it. This Great Rift slithers its way from Sagittarius to Cygnus. It gives the Milky Way its variegated appearance. Herein lies the irony of observing the Northern Coalsack: viewing it is like staring into the eye of some demonic spirit while simultaneously you are awestruck by a transcendent beauty. This dismal sea is flanked by two luminous bands of the Milky Way that make this piece of celestial eye candy worth relishing.
We may not have the navigational, morale and logistical concerns of Columbus and Vespucci. With a good star chart or a Go-To telescope we will not have weeks of endless cosmic ocean to cross to reach our destination. Secured in our holds will be our telescope, accessories and the all-important Oreo cookies. We may have to endure a long night away from our families but that’s the sacrifice of exploration. After all, it wasn’t easy for the ancient seafarers either. Bon voyage!
Searching for Diamonds in the Celestial Haystack
An AFSIG article by Paul Trittenbach
A long time ago there was a violent explosion and nearly nothing was left in its wake! A supersonic shockwave roared from the heart of the explosion and debris was hurled in every direction. There were no known witnesses to the great cataclysm. If anyone was around at the time, there would’ve been no survivors. All we have is the forensic evidence that tells us of a violent and horrible death.
When Shakespeare wrote of the struggles of humanity he could have just as easily been penning an exposition on the stars. Destruction and creation are part of the cycle of the universe. They are also the fabric of our literature and movies. There are those who burn out quickly but are remembered in legend because they shined so brightly. There are those who live long, moderate lives and die with little more than a stellar last gasp. And there are those that convulse before dying in powerful explosions, building monuments to their lives.
As our earth races around the sun and turns to face the summertime stars,
a dense murky patch of clouds and dust whorl overhead. We are facing in, through the Scutum-Centaur and Sagittarius arms of our galaxy, into the bowels of the Milky Way. Of the constellations that reside there, one of them, Sagittarius, is the focus of our attention this month. Here reside a couple of monuments to the lives of stars that once burned brightly. They are also popular summertime targets for amateur stargazers.
When Charles Messier cataloged M8 he was penning it into his list of celestial objects to avoid. It became one of 109 objects that were relegated to his “don’t see” file, but I recommend that you go there even if you have been there before. Messier 8, or M8, or the Lagoon nebula is an enormous interstellar cloud of gas and dust, the remains of the star that once burned brightly. It is classified as an emission nebula. Nebulae of this type are described as localized regions of ionized gas which emit light at various colored wavelengths, most of which are not visible to the human eye. M8 is located approximately 5200 Light years (ly) from our solar system and occupies a space of 140 ly high by 60 ly across.
M8 appears pinkish in color in time-exposure images, a flower in the celestial garden. This is due to ionized hydrogen (HII). But to our eyes M8 appears gray in color. This corresponds to the doubly ionized oxygen present and accounts for why the nebula is more vivid when viewed with an O III filter. The gases emit colors because they are ionized by the ultraviolet light emitted from an energetic white dwarf — the beating heart of the nebula. Hubble Space Telescope (HST) images show details of swirling twisters of gas and dust moving throughout the nebula. These twisters of dust and gas are the result of the difference between the hot and cold areas of the gases themselves.
Nature dictates that in order for a celestial mother to give birth it must die. In this case a violent explosion rips apart a star to create nebula which becomes a stellar nursery. M8 is also a complex of multiple structures — including a large open star cluster NGC 6530, Herschel 36 — the star that drives the nebula — and the Hourglass. NGC 6530 is a young, loose star cluster — most likely created within the nebula itself — composed of 50 – 100 young stars about 2 million years old. Off-center within the nebula is the Hourglass, a bright feature which appears to be a star forming region.The dark regions of the nebula are Bok globules, protostellar matter which under accretion forms the new stars in this nursery.
Our next flower in the celestial garden is Messier 20. M20, the Trifid nebula is next door to M8, astronomically speaking. Its name is derived from the three-lobed structure of the nebula. The Trifid nebula is a bonanza among nebulae — composed of three nebulas in one. The Trifid nebula is located at the same distance from us as M8 and astronomers believe that the two are closely associated, perhaps developed of the same origin. Like the Lagoon nebula M20 is a cocoon of interstellar gas and dust, and a stellar nursery.
This complex of emission, reflection and dark nebula is a combination of ionized gases of hydrogen, sulfur and oxygen. As with M8 this nebula appears gray to our eyes and images reveal a blue reflection nebula and red emission nebula nested together. Again, an O III filter will enhance the visual details in the telescope. The three lobes of M20 are separated by the lanes of a dark nebula, Bernard 85. Clouds of protosetllar Bok globules, through the influence of gravity, accrete to form new stars. But new stars currently being born within M20 are likely to never mature because the star that fuels the nebula is eroding away and will be unable to continue powering the nebula and its stellar hatchery.
Images by the HST reveal fingers of Bok globules amid dust and clouds within the nebula and the embryonic stars being created within. Detailed analysis in various wavelengths of light reveal that in these nearly opaque, cold clouds of protostellar matter material is metamorphosing into nascent stars; the term cocoon seems apropos. We will not be able to reveal these details with our telescopes but understanding the mechanics of the subjects in our eyepieces only adds one more piece to the vast cosmic puzzle. I also believe it makes our stargazing more interesting.
Binoculars and a telescope of any size will allow you to view M8 And M20. Take your time to look for the details in the wispy clouds of this nebula. Vary your magnification to tease out details and get a better look at features such as NGC 6530 in M8. Dark skies are always best for separating details so take advantage of our CAC or TIMPA facilities. And on all of those nights when the weather prohibits stargazing take the time to revisit these targets in your thoughts — stroll through the celestial garden and reminisce the remnants.
Finding a Diamond in the Cosmic Haystack
An AFSIG article by Paul Trittenbach
Located 1.4 billion kilometers (9.6AU) from the Sun is the second largest planet and sixth planet of the solar system: Saturn. Its beautiful ring structure makes it the most popular planet among amateur astronomers and the public alike. Like Jupiter, Saturn is a gas giant planet composed predominantly of Hydrogen and Helium.
Saturn was the most distant planet known to the people of the ancient world. It was not viewed through a telescope before 1610 when Galileo Galilei turned his 30-x refractor upon it. To his amazement, he saw a pair of objects on each side of the planet, and sketched Saturn as a three-bodied world. After numerous observations, he sketched these lobes as handles attached to either side of the planet.
In 1659 the Dutch astronomer Christian Huygens, using a more powerful telescope than Galileo’s, proposed that Galileo’s handles were in fact a thin flat ring that surrounded the planet. Later in that century, in 1675, the Italian born astronomer Jean-Dominique Cassini observed the division between what are called the A and B rings of Saturn. It is now known that the gravitational influence Saturn’s moon Mimas is responsible for this 4,800 mile-wide division, known as the Cassini division.
Saturn’s volume is 755 times greater than that of Earth. The winds of the planets’ upper atmosphere can reach up to 500 m/s, four and half times the speed of the fastest hurricane on Earth! Combined with heat rising up from the planet’s interior, these winds create the yellow and gold bands of the atmosphere. A day on Saturn lasts 10.7 hours and one year is equivalent to 29 Earth years.
Saturn’s rings are composed predominantly of water ice. The rings contain more than 23 times as much water as all the oceans of Earth. They consist of seven separate ring structures extending up to 282,000 km from the planet; about three quarters of the distance between Earth and the moon. The depth of the ring system is approximately 10 meters.
Saturn has 62 known moons. The largest moon, Titan, is bigger than the planet Mercury and the second largest moon in the solar system (only Jupiter’s Ganymede is bigger). Titan has a thick nitrogen atmosphere, similar to the early atmosphere of Earth. On Titan, the cold atmosphere causes methane — a normally gaseous compound on earth — to precipitate out of the atmosphere as rain. Titan has large lakes of methane and planetary scientists are interested in it because of its potential to harbor basic life. Further study of Titan may help scientists to better understand early Earth. Titan is the only other moon in the solar system where NASA has landed a probe.
Saturn’s moon Titan was discovered by Christian Huygens in the year 1655. Giovanni Cassini followed up with the discovery of the next four moons: Iapetus, Rhea, Dione and Tethys. In 1784 William Herschel discovered Mimas and didn’t sell at this. More than 50 years had passed before the discovery of Hyperion and Phoebe. As the size and resolving capacity of telescopes increased, so too did the number of discoveries of new moons around Saturn. Additional discoveries came via robotic probes, such as the Cassini mission earlier this century.
Iapetus is a two-faced world — having one side that is highly reflective and as white as snow and another side as dark as black velvet. Mimas has an enormous impact crater on one side that nearly split the moon and half. The moon Enceladus has a fractured surface where water can escape, through evaporation, into the atmosphere. This displays evidence of active volcanism on the planet. Phoebe and several other moons, orbits retrograde to the planet. Sixteen of Saturn’s moons orbit and a tidal lock with the world, always keeping one face toward the planet.
Studies by NASA’s Cassini probe indicate that Saturn has a dense core of rock and ice, solidified by Saturn’s intense pressure. The core is surrounded by a metallic liquid hydrogen layer — similar to that of Jupiter, but considerably smaller. Saturn’s magnetic field is 578 times as powerful as that of Earth, but still smaller than Jupiter’s.
The rings, and most of the moons lie totally within the influence of the planet’s magnetosphere. The magnetosphere is a magnetic field surrounding a planet, where electrically charged particles of the solar wind interact with the magnetic fields of the planet. This is the area in which planetary auroras are created.
Saturn can be easily observed through a small telescope, making it accessible to anyone. The deadline for our observing season, however, may be closing within the next month as monsoons begin to dominate our southwestern sky. The planet reaches opposition on the morning of June 3 at 1:00 AM. But any time throughout the month of June and the entire summer will be good for seeing the planet, which is available to us until October.