Next Meeting: Friday, November 4, 2016
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.
Location: USGS Building, Room 253 (520 North Park Ave)
Contact: Dennis McMacken
OPEN TO THE PUBLIC.
Come and learn your way around the night sky to add to your observing enjoyment. Meetings are on the second Thursday of each month.
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 like from 300,000 stars shining 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 to 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 a 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 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!
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!
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.
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.
TAAA Support of Public Mercury Transit Event At Brandi Fenton Memorial Park
By Jim O’Connor
Pictures by Jim Knoll
TAAA has a long history of supporting Pima County Natural Resources/Parks and Recreation and their active astronomical outreach programs. Usually these events are at either the Ironwood Picnic Area on the West Side, or Agua Caliente Park on the East side. For the Mercury transit, however, the venue would be Pima County’s Brandi Fenton Memorial Park. TAAA has performed public Astronomy Festivals at that location in the past, so it was a familiar location.
The event was scheduled from 8 AM through 10 AM, which was a segment in the middle of the transit. The transit itself was forecast to occur from 4:12 AM through 11:42 AM, with sunrise around 5:35 AM, so most of us planned on being there at our earliest convenience, and to stay through the end of the event.
I tried to arrive by 6:30 AM, but my guess on how long the drive would take was wrong, and I didn’t show up until around 6:40. Alan Klus had his dual mount already on the sun, while Jim and Sue Knoll were finishing their setup. As I was setting up, Ron Brewster and Bill Yohey arrived and began setting up, as well as a young lady with a 10” Dobsonian reflector who I did not recognize. We ended up with a mix of white light and H-Alpha scopes. I thought about both options, and while my white light choice would be 90mm, larger than my 60mm Lunt solar scope, I also wanted to take a chance on more solar artifacts being available in the Lunt. Jim Knoll also has Lunt 60mm, but while I have a B600 blocking filter, Jim has a B1200, resulting in a tighter frequency band and more detail in his images. This holds true in eyepiece views, but I push mine through a Mallincam Xterminator, and the resulting image in the attached 19” monitor does well at pulling out details. Unfortunately, I left my laptop and camera home, so I couldn’t capture transit images, nor any of the crowd we had attending the event. Jim Knoll provided some photos he took.
As soon as I got completely set up, the first solar image showed Mercury right where it should be. When Jim commented that he was getting prominences in his view, I altered my exposure time and, sure enough, in my view there were two fountains at the top of my screen, one at approximately 11:30 on the face, and the other at about 12:30. Each was three to four Earth diameters, and resembled spraying fans. Positions on the screen are kind of irrelevant, because not only does the telescope and blocking filter diagonal provide an image rotation, but the image orientation itself is dependent on the orientation of the camera in the eyepiece opening. I readjusted the shutter speed to lose the prominences but highlight the surface characteristics. The sun itself was very entertaining, with multiple wide, long, and arching filament groups and several dynamic, bright white active regions. During the morning, I had about 65 or more visitors. Everyone was amazed at the view, not only the crisp, black disk of Mercury, but all of the other artifacts that varied over time. I had two large poster sets at the table; one had solar characteristics, examples, and stellar evolution, the other had displays of the Mercury transit, an image of Mercury, and a fact sheet about Mercury. The visitors to my setup were all very excited to see not only the transit itself, but all of the solar action. I made sure to tell everyone about Saturday’s TAAA Astronomy Festival at the same location. I was also able to hand out about 10 solar tattoos to young children in the visitor groups. Some of the visitors were bicycle riders and people walking their pets who were pleasantly surprised to find us, and it was a great educational opportunity on the nature of the orbits in the Solar System, and also to discuss stellar evolution. There were even some folks, young and old, who wanted to discuss the varying forms in which stars end their existence. We were not terribly busy, and the chance to spread the information was great to have. Toward the end of the session, after about 10 AM, I enclosed the monitor in a box to cut down on reflections from people’s clothing onto the screen, but the matte surface of the monitor does well on its own to put out a good image, as long as the sun is behind or to the side of the observer. The visitors did seem more comfortable with the shadow box, though. And about a dozen people took smart phone pictures of the great solar images.
Many thanks to Bill Yohey and Jim Knoll for helping me get all my equipment over to the truck after it was all over. And thanks to PCNRP&R for having such a great educational event. We opened a lot of minds, and sparked a bit of curiosity in the crowd that showed up.
South Rim Coordinator
Grand Canyon Star Party
Only one transit observation has trickled in from John Kalas, but will include a surprise below. I’ll include a couple pictures too. Here is John’s:
Mercury Transit – 5/9/16
I awoke at about 7:00 am and took my 11×80 giant binoculars with solar filters out in the backyard to assess the transit and make the big decision of whether or not to lug out the telescope. I should have set up the telescope the night before and left it parked overnight, so it would be accurately aligned for the transit but I was lazy.
The transit was about mid-way, so I decided to get out the scope. By about 8:00 am, the Astro-Physics 130mm refractor with a Thousand Oaks white light solar filter on an A/P 600 mount was ready-to-go. On went the Canon 60Da DSLR camera at prime focus and I started experimenting with the manual settings of exposure time and ISO speeds. After several trips into the house with the camera’s memory card to review the images on the computer, I settled on 1/8000th of a second exposure time and an ISO of 1600. Being that I didn’t have a precise polar alignment, I had to slightly re-align the sun in the camera’s view finder for every shot. Shown here is the start image and the last image.
A Few Shots from the Mercury Transit
With the Mercury transit already underway at sunrise, I was visualizing a shot of “Mercury rise” as it cleared the Catalina Mountains, so on Saturday I scouted a few locations for a clear view – tough to find in the metropolitan area with trees, power lines and easy access. I finally found one near the east end of Roger where it meets the Rillito Wash near UA Farms.
Since I never use an alarm clock, I actually had to test it to see if it worked for my 4:50 wake-up call so I could drive the mile or two and set up. Conditions looked great – the picture at left shows my setup – the TEC 140 (plus 1.4X Canon extender) on my Alt-Az mount, with the location on the right slope of a hill. The shot, close to my visualization, except for perhaps a saguaro or two, is shown at right. Mercury had just cleared the slope at lower left.
What is interesting to me are some of the atmospheric effects of the low sun. We all know about the “green flash” as the atmospheric dispersion gives any setting object a green or blue upper edge and a red lower edge. You can see it on the above image. But if you examine the image of Mercury, or even the sunspot, you can see the inky spot has a reddish upper edge, and blue/green lower! Of course it is caused not by the black dot, but rather the illuminated upper edge of the lower edge of Mercury is green… An enlargement is shown at left.
At his point I retired to home, where I had setup and aligned the AP1200 the night before in the back yard. Spending about 30 minutes figuring why the scope wasn’t tracking (Duh – in my sleep-addled state I’d hooked it up wrong!). Eventually I got underway – fortunately the trees blocked the low sun, so I got going about mid-transit. So I’ve got hundreds of images thru the thing – perhaps they’ll get turned into a movie someday. Shown here is a 2-image stack very near 3rd contact showing a full-resolution shot of the TEC+1.4X extender+Canon XSi camera. I couldn’t be happier with the resolution, just my processing skills how to proceed with a few hundred images!
I hope all who had a chance to observe had a great Transit!
Oh Yea – the surprise!
Since Tom Polakis just spoke to the TAAA 5 weeks ago about time-lapse imaging, I’ve absolutely GOT to show you his treatment of today’s transit! Using a Lunt100, he took high-speed video of the last 10 minutes including egress, and used about half the frames to make 31 frames of fantastic! Gif is shown here, and the link to his pbase gallery is here. “Mike drop” here… Just amazing!
Most Tucson amateur astronomers know what happens on the first Friday of the month – the monthly meeting of the Tucson Amateur Astronomy Association (TAAA)! Arguably living in the astronomy capital of the world, we have some pretty good meetings. With the Kitt Peak National Observatory, the Planetary Sciences Institute, Steward Observatory and the Lunar and Planetary Lab all headquartered in central Tucson, we are rarely lacking for world-class lectures about the universe or latest data from spacecraft. We even get great lectures from TAAA members themselves, some of them working at the above institutions!
Last night was the first Friday, so of course, we got together, but our normal lecture hall at Steward Observatory was being used for final exams – it is that time of year! So we arranged to meet across the street at the auditorium of the Lunar and Planetary Laboratory. The location fell into the theme of the evening – celebrating the history of LPL. The traditional Beginner’s Lecture was a showing of the great documentary “Desert Moon”, a 2014 movie by Jason Davis. Using archival footage as well as interviews with early employees, it tells the story of how LPL played a central role in the space race and eventual landing on the Moon. Gerard Kuiper, who founded LPL in 1960 is at center in the right image, and Ewen Whitaker, one of the main interviewees, is at right.
The movie is a testament to Kuiper’s leadership and assembling this team around him, most just barely out of their teens! They played central roles as Kennedy surprised scientists by declaring the Moon as a goal for NASA. Starting with the lunar atlas Kuiper started at Yerkes Observatory, after founding LPL they supported virtually all the lunar missions leading up to the landing. Fortunately, the movie Desert Moon is free for viewing on-line, and at 35 minutes long, is a great watch, even on a computer screen. My favorite scene is the un-narrated final scene when some of the now “old-timers” who played such central roles, put their swagger on and strutted down the University Mall – shown at left!
The main meeting started promptly at 7:30, and after a few announcements and business (Springtime Board Elections!) the main lecture started – given by LPL director Timothy Swindle. He admitted that the first half dozen slides of his normal talk were well covered by “Desert Moon”, so modified his presentation somewhat. He also announced that much of what he presented was covered in a recent book, recently published by UA press – Under Desert Skies by Melissa Sevigny. Reading her book would likely be a great addition to the information gleaned from Dr. Swindle’s presentation.
Dr. Swindle points to the launch of Sputnik in the 50s, and the 6 week period in Spring of ’61 in forming the direction of LPL’s mission to the Moon and beyond. So the developing space race kept funding levels high and the department focused both on the Moon and a fledgling planetary space program. After the successes in the Moon landings, UA continued involvement in the Pioneer, Voyager, Cassini and Mars missions.
He told the story of Lujendra Ojha, an undergraduate from Nepal working on a student project with data from HiRISE, under the direction of principle investigator Alfred McEwen, and discovered “streaks” on the inner walls of craters and gorges that follow up spectroscopy showed was briny water – one of the first direct indicators of water on Mars.
He also told the story of Richard Kowalski. One of the primary research works of Steward and LPL consists of searching for Near-Earth Asteroids with the Spacewatch and Catalina Sky Surveys. Kowalski is the ONLY observer to discover objects BEFORE they struck the Earth, one exploding over Sudan, the other striking the Atlantic Ocean. He is shown at right holding a small piece of the asteroid/meteor that landed over Sudan.
He closed out his talk with the latest mission coming out of LPL – the OSIRIS-REx mapping and sample return mission to an asteroid. Facing a launch this September, it arrives at Bennu in 2018, and returning with its precious cargo in 2023. Answering questions for a good long time, it was a great talk and enjoyed by all.
After the meeting’s conclusion, most stayed to interact outside the auditorium over snacks. Another great meeting! The next one will be the day before the Grand Canyon Star Party starts the first weekend of June!
A rather rare event will be happening on Monday May 9 — Mercury will appear to move across the face of the Sun. For us in Tucson, the transit will already be underway when the Sun rises at 5:32 am. The Tucson Amateur Astronomy Association (TAAA) will have several Solar Telescopes set up at Brandi Fenton Memorial Park starting about 7:30 am. We’ll be there until at least 10 am, but will hang around as long as there are people interested in viewing the Transit. The Mercury Transit will end at 11:39 am Tucson time.
Mercury Transits are fairly rare, with only 13 or 14 per Century. The last Mercury Transit was November 8, 2006 and the next one will be November 11, 2019. After that, we’ll have to wait until 2032 for the next one. Mercury Transits only happen within a few days of May 8 or November 10 of any given year. The reason they don’t happen every year is because Mercury’s orbit is inclined 7 degrees to Earth’s Orbit, so most of the time, Mercury transits just above or below the Sun from our perspective.
Join TAAA at Brandi Fenton Memorial Park on Monday May 9th to view this rare event.
Join the Tucson Amateur Astronomy Association (TAAA) on May 14th, from Noon to 9 pm at Brandi Fenton Memorial Park to celebrate National Astronomy Day. This will be a fun-filled day and evening for the entire family. We will have solar telescopes for safe viewing of the Sun and interactive exhibits for everyone during the afternoon. There will be telescopes for viewing deep sky objects in the evening such as Jupiter, star clusters, galaxies, nebulae, and Mars (late evening). We will have a door prize drawing at 7 pm for a 50mm telescope (must be present to win) and a Walk Around the Night Sky presentation around 7:30 pm. The complete schedule is below.
Safe Solar Viewing of the Sun Noon – 6:30 pm
Interactive Astronomy Exhibits Noon – 6 pm
Make Pocket Solar Systems & Sun Dials
Make an impact crater
Door Prize Drawing (must be present to win) 7 pm
50 mm Refractor Telescope
Night Sky Viewing 7:30 – 9 pm
Walk Around the Night Sky Presentation 7:30 pm
Help with personal Telescope All Day/Evening
Bring your personal telescope to receive
assistance in setup & operation