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.

MARIA 

My purpose is, indeed, a horse of that colour.

SIR ANDREW 

And your horse now would make him an ass.

MARIA 

Ass, I doubt not.

SIR ANDREW

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.