Wednesday, January 31, 2007

Baby Stars

2/4/07 – 2/10/07

by C. Zaitz

One of the most magnificent things to “see” in the sky is the Great Nebula in Orion. However, it’s not so great to the naked eye on a chilly evening in light-polluted Metro Detroit in February. Your eye might detect a little fuzziness, a little hazy area around the stars at the tip of Orion’s sword. One of the “stars” is really the nebula, but the significance of this little blur in the sky might be lost by a casual glance.

If we look a little deeper, the fuzzy blob reveals one of the most incredible places in our galaxy. The nebula is a huge, diffuse cloud of gas and dust, some 1,500 light years from earth. The nebula formed from an even more diffuse cloud of molecular gas, slowly brought together into denser pockets that eventually formed stars. We now see pockets of gas and dust forming bubbles, or protoplanetary discs. Perhaps stars with planets are forming, or maybe a double star system will form. We already see baby stars in their formative years. Embedded within the wisps of colorful gas of the nebula is a group of four hot, blue stars in a formation we call the Trapezium, at least one of which is a double star. These stars can be seen easily with a small telescope, and they mark the spot where nearly 1,000 sun-like stars are just being born and are beginning to shine. It’s a stellar nursery, similar to the famous one we’ve seen in the Eagle Nebula.

Right now the area is clouded with dust and gas, lit in abstract colors by the intense fires of the newly born stars. Astronomers say that eventually the nebula will be blown away or absorbed and what will be left is something similar to the Pleiades or the Beehive cluster. These are called open clusters, and remind me of ripe grapes hanging in clusters in space. They are beautiful, but they relatively devoid of the colorful gas clouds that make the Orion Nebula so stunning. When we look at the Nebula with telescopes and make long-exposure images, we see an incredibly breathtaking work of art, nature’s best, hanging low in the constellation of Orion.

So how do you go about seeing the Orion nebula? If you begin on the internet, by looking at the beautiful full-color shots from the Hubble Space telescope or even large ground-based telescopes, you will not be disappointed. But if you start there, you may end there. You may never get the thrill of seeing the nebula live, in person, through a telescope. And there is something special about seeing deep-space object, or things outside our solar system, with your own eyes. Therefore, finding a winter star party is your best bet for seeing the nebula. Amateur astronomers are famous for sharing their expensive telescopes with anyone who wants to see the sky, and even some folks who were just innocently passing by. I have even been known to cajole people into taking a glimpse. Though folks may be tentative at first, it only takes seconds to be converted into a believer.

Who is throwing a star party at this time of the year? If you do a quick internet search for our local amateur astronomy groups, you’ll be surprised. As long as you bundle up in layers, winter star gazing can be quite exhilarating and fun. And there’s oh so many ways to warm up afterwards, sharing laughs and warm beverages with new friends.

Until next week, my friends, enjoy the view.

Tuesday, January 23, 2007

Catch a Glimpse

1/28/07 – 2/3/07
by C. Zaitz

We have a somewhat rare opportunity to catch a glimpse of a planet that usually hides in the glow of the sun. Little planet Mercury should be visible in the western sunset glow until about the 7th of February. You’ll need a pretty flat western horizon and a little patience to see the diminutive and shy planet, but once you see him, you’ll never forget it.

Here’s why: as you look toward the west at sunset, you can see our entire inner solar system. Venus, shining brightly even a half hour after sunset, will be the first thing you notice. You can’t miss her; she is the brightest celestial object after the sun and moon. Venus dominates the sky after the sun goes down. She was named for the goddess of love and beauty, for the obvious reason of her glorious glow. She shines so brilliantly that she can be mistaken for man-made or even alien craft. If you watch her for a minute or two, you’ll notice her steady light. This is no plane or UFO, it's the brilliant evening "star."

Once you find Venus, you should look a little down and to the right to find Mercury. This planet was named for the fleet footed god of the Romans, Mercury. As the closest planet to the sun, his orbit is small and fast. He whips around the sun once every 88 days. But it’s not his speed that makes him hard to see, it’s the fact that the smallest of the planets is never very far from the sun. When you look for Mercury, you’ll have to balance waiting for the sun to be low enough for the skies to darken, but not waiting too long so that it sets. Don’t give up on Mercury, though- he’s worth the wait. Seeing Mercury is like the thrill of seeing a rare but hidden flower or bird.

Standing on planet Earth, third from the sun, we can skim past our own horizon, looking past our own atmosphere and see Venus and Mercury rushing in their trips around the sun. The inner solar system is very busy, and relatively close together and dense, just as when the solar system first formed. Most of the mass and heavy elements literally gravitated toward the middle. These inner planets are dense, fast and alone. No moons tag along to hinder the orbits of Mercury or Venus.

Further out, and seen later in the evening, are the giant planets Saturn and Jupiter, and even Mars. To see Saturn, you don’t have to wait too long after sunset. Look toward the east around 9pm and you’ll see the giant gas planet glowing near the constellation of Leo. Leo reminds me of a backwards question mark, but to see the whole constellation, you’ll have to wait up till midnight or so. As long as you’re up watching the skies, you might as well wait till morning, around 7am, when you can catch a glimpse of the last two planets of the night. Jupiter will be hanging low near the glow of sunrise, and planet Mars, dimly glowing, will be even closer to the horizon. But if you have a clear view of the east on your morning commute and catch a glimpse of these planets, you will have seen the entire visible solar system over the course of one night. What more could you ask for?

Until next week, my friends, enjoy the view.

Wednesday, January 17, 2007

More Than Meets the Eye, Part II

1/21/07 – 1/27/07
by C. Zaitz

It’s hard to watch the birth of a star. Apparently stars like to form in private, shrouded by opaque clouds of gas and dust. When giant molecular clouds in space collapse from their own gravity, one outcome is a star with planets. Often, rather than planets, two or more stars form. Scientists wonder what causes one and not the other, but stars pull a self-made curtain around themselves during their birthing. With better telescopes, however, we’re beginning to see more. Over half the stars in the sky are multiple star systems. Here’s what we can see.

Sometimes we can detect a system of two stars, called binary stars, through spectroscopy. This is the study of the light we collect from them. Normally we can spread the light we collect from stars out into a spectrum so we can learn all manner of things about the star; its composition, perhaps its distance, speed and direction, and even how old it is. It’s amazing what a little starlight can do. But sometimes we notice that the spectrum from a star is odd. Part of it is shifted toward the blue end of the spectrum, and part toward the red. Shifting of spectra is a curious thing; it tells us that the star is both coming toward us and away from us. Impossible! Unless, perhaps, it’s not just one star, but two stars in orbit, with one coming toward us and one going away. In fact, this is how we discover many binary stars.

Sometimes we see stars dimming and brightening, apparently for no reason. However, as adults, we recognize that things usually have reasons, as bizarre as they may be. Sometimes when stars orbit each other, they happen to be in our line of sight such that they will eclipse each other. They are known as eclipsing binaries. One star, in the constellation Perseus, is a very famous eclipsing binary star. Algol is normally about 2.3 magnitude, easily seen with the naked eye, but every 10 hours or so it will dim about 68%. This is when its companion moves in front of our line of sight, Since the companion star is dimmer, the total amount of light we get from Algol lessens. Perhaps that’s why it is named in Arabic, “the ghoul.” Algol is often referred to as the winking eye of the demon.

If a star has several companions, it becomes a star system. A famous system of stars is the middle star in the handle of the Big Dipper. Just using your eyes, you can usually detect two stars instead of one. Mizar and Alcor are close, but not close enough to be a double star system. We call that a visual binary- they appear close in the sky, but are not that close physically. However, the brighter of the two, Mizar, is actually composed of two stars, Mizar A and Mizar B. Furthermore, Mizar A is composed of two stars, as is Mizar B, so we have a system of two sets of twins orbiting each other. Amazing. But you can’t see this with your eyes. It’s fun to look at Mizar and Alcor anyway and imagine the complicated gavotte those stars must be executing.

Look to the north to see the Big Dipper, and if your eye is caught by a shiny light in the west at sunset, don’t be alarmed. It’s only the eye-catching, attention hogging Venus, showing off in the fading twilight.

Until next week, my friends, enjoy the view.

Wednesday, January 10, 2007

More Than Meets the Eye, Part I

1/14/07 – 1/20/07
by C. Zaitz

One of the more interesting facts about the night sky is that most of the stars you can see are not alone. Though they look like single points of light, there’s more than meets the naked eye. Some stars have companions that are too dim and small to see, and some have planets which are too dim and small to see. Either way, there is much more going on than we realize with those distant stars.

Our sun is one star that happens to sport planets. Planets are the result of a process that is not completely understood, so I will give you the short version, leaving out details in favor of getting the bigger picture.

A long, long time ago there was a cloud of gas and dust, the remnants of a star that once used to shine, but had long ago blown itself to bits and had created heavy elements in the process. This cloud was unimaginably huge, and all the little bits of it were moving in some direction. Eventually, the muddled bits tended to go in one direction in particular, flattened out, colliding and growing together under the force of gravity. Most of the bits came together in a great ball, which eventually became so massive that the inner bits were crushed and made to fuse, causing a chain reaction that produced prodigious amounts of energy. The sun was born.

Meanwhile, there was a still a great disk of gas and dust further out. The heavier stuff, like rocks and dirt and gold and silver, tended to be nearer the middle, forming the rocky inner planets. The lighter stuff, like hydrogen and helium and other wispy gases, collected further out in great blobs we call the gas giant planets. The little inner planets were heavy and cleaned up their orbits pretty well. Of the four planets, there are only three moons. Earth’s moon is the only respectable looking satellite, since Mars has two overgrown potatoes orbiting it.

Beyond Mars and the asteroids, things get more complicated. The four gassy planets developed rings and multiple moons. The rings are like millions of tiny, shattered ice moons. Some of the moons, and even some planets, have odd scars and orbits which indicate violent collisions, and possibly intense gravitational wars which have shaped the outer solar system. Recently, we have discovered a host of small bodies beyond Neptune which are now called dwarf planets. Pluto is of this realm, but more Pluto-like bodies are being discovered all the time.

As we look to other stars, we notice that a few hundred seem to have bodies orbiting them. These bodies are huge compared to our planets, but not big enough to be stars. Better telescopes will surely reveal smaller, more earth-like planets around stars. In fact, some astronomers estimate that nearly half the stars in the sky have planets. That’s a lot of planets. I wonder what those planets are like. Some are probably rocky and small like our earth. Will they house aliens? Will we someday meet Klingons? Or maybe the truth will be stranger than fiction. The exciting part is that someday we may be able to answer the question: are there aliens living on other planets. I hope the answer isn’t “no.” How dull!

Next week we will explore the strange multiple star systems that can also form instead of planets.

Until next week, my friends, enjoy the view.

Thursday, January 04, 2007

Sitting in

I sat in with Jay and guest at last friday's broadcast, live Journal. It was pretty darn fun. A(No longer) archived on the WHFR on the website in the bottom right corner under "WHFR Journal Podcast Archive." (only the latest epsiode is there... but stay tuned, I'll try to get it all here one day) I knitted a bunch and they made me laugh. Well worth it! I giggled through the whole thing.

Pretty Pleiades

1/7/07 – 1/13/07
by C. Zaitz

The Pleiades are so very pretty and interesting that they deserve some attention. You might know them as the Seven Sisters or might not know their name, but you’ve probably noticed them in the winter sky. They are often confused with the little dipper, but they are much tinier. In suburbia they are ephemeral, but if you are patient you can usually spot them in a cloudless sky. They are definitely worth knowing about, so let’s get to know them a little better.

The Pleiadian sisters are famous. Many cultures have seen and even worshipped the Pleiades, though they have been called many things in many languages. They rise in the east before Orion the Hunter, and he chases them across the sky all evening. The sister stars have even more mythological starry sisters, known as the Hyades. You may have noticed them as well, if you’ve seen the “v” shape of stars to the west of Orion. Look for Orion’s shiny belt of three stars and point up from there to find them. The “v” marks the face of Taurus, and the brightest star marks his eye. This star is named Aldebaran, which in Arabic means “the one who follows.” Aldebaran is not one of the Hyades, but the rest of the stars are. Some say the Seven Sisters are being chased by Orion, since the mighty hunter was notorious for having an eye for the ladies. If so, Orion will have to wait a very long time. The Pleiades are “running fast.”

Though they are often called “the Seven Sisters,” the faint group of stars is what we call an “open cluster” of many more than seven stars. Over 200 stars are collected in an area of space some 10-30 light years across. That is pretty dense compared to most of space, but open clusters are still less dense than the ancient globular clusters of stars we also find in the outskirts of galaxies. The Pleiades are known as the brightest open cluster of stars in the sky. Though they are not quite as pretty, the Hyades are much closer, “only” 130 light years away. The Pleiades are well over 400. If they were as close as the Hyades, imagine how spectacular they would be in our night sky!

The Pleiades were the daughters of Atlas, the man who was forced to carry the weight of the world on his shoulders, and Pleione, a sea nymph. The daughters all had beautiful Greek names: Maia, Electra, Taygete, Alcyone, Celaeno, Sterope, and Merope. Maia was the mother of Hermes by Zeus himself, and all the sisters except Merope consorted with gods. Merope was wooed by Orion and is said to have married Sisyphus. Since she was not of the immortal realm, her star faded. Some say that is why we can only make out six of the seven stars today.

Scientifically we know that the stars are receding from us, and eventually we may have difficulty in seeing any of the sisters with the naked eye, but until then, please enjoy them with binoculars, or just with your eyes. You can see the pretty stars all winter long.

Until next week, my friends, enjoy the view.