Thursday, July 31, 2008

What I loved best about my Summer Astronomy Adventure

By C. Zaitz

I only noticed the thin air when I was either walking up a hill or getting excited.
This night I was doing both. A week from when we arrived in Arizona on a ten day “Astronomy Adventure,” a dream finally came true. I was walking up hill to an observatory, excited and breathless, ready to spend five hours shadowing astronomers and telescope operators on their jobs.

On the first night, the two astronomers whom we met were very polite and welcoming to us. My partner and I were very thrilled to be there and a little “starstruck” to be in the big leagues, which may have reassured them that we wouldn’t hamper their work. Our main guide was very talkative and funny, giving us humorous glimpses into what goes on in the dome all night long, and how he keeps himself awake when we hits the “wall” in the wee hours of the morning. The other astronomer, a young grad student, was nice enough to draw me pictures of her research on intermediate Seyfert Galaxies. These are galaxies with extremely bright cores, thought to be gigantic black holes. Her research had to do with figuring out the orientation of these galaxies, since the hot topic in AGNs or Active Galactic Nuclei galaxies is that they may be the one object behind three faces; we’ve seen them as quasars, blazars and Seyferts depending on their orientation.

The astronomers also operated the telescope, and watching them do that was also awe inspiring. Though we didn’t get to look through the instrument ( we had to bite our tongues not to call them “scopes!”) we got an excellent view into what makes a research astronomer tick. I will take that glimpse back into the classroom to enrich the picture I paint about what scientists can do for a career.

Friday, July 11, 2008

Where Are the Stars?

5/11/08 – 5/17/08
by C. Zaitz

We tend to think of the night sky as having an infinite number of stars, but in all reality we can only see one or two hundred in our local sky. This fact seems to contradict poems and prose that refer to the sky full of "countless stars." So where are all the stars?

From earth, we see the individual stars that make up the familiar constellations like Orion and Leo. Stars like Betelgeuse and Sirius are either fairly close, or really big, or both. They appear much brighter than the rest of the stars in the sky. They are so noticeable that they were granted proper names, rather than just catalogue numbers like the rest of the visible stars. But there are only a few hundred bright stars with proper names. The rest are either just too far away, too faint and unnoticeable. We see them as the blurry path in the sky called the Milky Way.

When we look up at night, nearly everything we can see is part of our galaxy. The Milky Way is home to several hundred billion stars in different stages of life and death. We only see several hundred of them when we look up at night due to light pollution from sources like civilization and the moon. On a dark, clear night away from a metropolitan area, maybe thousands of stars are visible. But where are the rest of them? Where are the other billions?

Our galaxy is a flat disk of stars with a bulge in the middle, like a flying saucer made out of sand. Each “sand grain” is a star like our sun, but there are other things in the galaxy, like clouds of gas and dust called nebulae. These clouds might be stars waiting to form, or stars that have exploded. Often when these giant clouds form stars, they form in big groups called clusters. When you put honey into a bowl of granola, the granola clumps around the honey. Imagine that gravity is the honey. Gravity causes the gas to clump and out of the clumps are born stars. Most stars that you see in the sky formed in groups, but over time they scatter. Our own sun seems to stand alone, but most likely formed in a group of stars that long ago scattered. Most of the stars in the Milky Way are too far away for us to see individually now. They are scattered throughout the galaxy, which is over 100,000 light years end to end.

Other clouds are from stars that have exploded, flinging their gas and dust back whence they came; cold, empty space. Dark clouds or nebulae block light from stars beyond them. As we look along the galaxy, along the flat disk of milky faraway stars, we can detect these dark clouds. They look like dark smoke hiding the bright stars behind them. The best time to see the dark clouds and stars of our galaxy is in the summer time. The Milky Way looks like a swath of milky light stretching from north to south overhead, but only from places where there are very few lights, or on an evening with no moon. Summer time is a good time because we often get to leave our cities and find places with fewer lights, lower populations, and a much better view of our home galaxy.
You may not see the billions of stars, but you'll get enough starlight in your eyes to appreciate our tiny place in the vast galaxy, the Milky Way.

Until next week, my friends, enjoy the view.

Saturday, July 05, 2008

Jewels in the Spring Sky

4/20/08 – 4/26/08
by C. Zaitz

If you like sparkly things, there is something in the spring sky worth looking at. We’ve been used to dashing from car to work, and back home, without so much as a quick glance skyward all winter long. But now we’re beginning to walk and jog after work, to play with the kids and the dog in the yard, and to notice the outdoors a little more. So what are we seeing in our spring sky? On spring evenings, the stars can glitter wildly as the moving air blinks and twinkles their light. Moving air causes the light from distant stars to jump around and blink on and off like Christmas lights. As pretty as it looks, it makes the image in a telescope look blurry. But when the wind dies down and the temperature rises, there are some spectacular sights to be seen. Two that I'd like to describe look like fuzzy blobs in the sky, but turn spectacular jewels through a telescope.

The first is a very famous fuzzy blotch that is very hard to see with the naked eye, but is one of the most popular destinations for telescopes and binoculars. It is called M-13, but we know it better as the Hercules Cluster. It is a giant group of stars called a globular cluster. Globular clusters are common in galaxies, but they are rebels in a sense. They don't generally ride the spiral arms of the galaxy like the rest of the stars. They can be found high above or below the plane of the Milky Way, in its halo. Spring is an excellent time to spot globular clusters, because we are looking out away from the plane of the galaxy, to the halo area where they live. The Hercules cluster is home to over a million stars, but the true beauty of the cluster comes from the fact that the stars are much closer together than stars in the rest of the galaxy. Instead of a 3 light year average separation, the stars of M13 are on average only one light year apart, making the cluster dense and very brightly sparkly. It's a trick I would use if I was a jeweler and had diamonds to set. The dense packing of stars in a globular cluster make them some of the most beautiful objects to see.

Another famous cluster seen in the spring is M44, known as the Beehive cluster. It is just in front of the sickle shape of stars that marks the head of Leo the Lion. It is one of the nearest and largest open clusters we can see, and therefore one of the brightest. You can see its fuzzy glow with the naked eye, but both clusters really shine when you view them through a telescope. Their true nature will be revealed as you begin to see the individuals making up these vast clouds of stars. Open clusters are made of young, hot, blue stars, and live in the plane of our galaxy, so they are different in appearance and make-up from globular clusters. If I were trying to match their character as a jeweler, I would select the brightest and clearest diamonds to set in a less dense, but still brilliant way.

To find these beautiful objects, it's always good to know your way around the sky. If you spend a little time in the spring with a flashlight and star map, you can see them for yourself. And who couldn't use some sparkly in their life?

Until next week, my friends, enjoy the view.