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All posts for the month February, 2004

Sunset on Mars

Sunset on Mars

When our great-grandkids living on Mars go out stargazing, this is what they might see as they wait for the Sun to go down and the stars to start popping out. I’ve always wondered what it will be like for the first Mars residents to haul out a telescope and check out the stars and galaxies and planets. You know how we always tell everybody to dress warm here on Earth, even in the summer? Well, Martian stargazers won’t have a choice. It’ll be “dress warm, wear a pressure suit, and bring along plenty of oxygen.” Or, maybe it’ll be “remote” observing, with the telescope set up outside and the observer seated at the computer, safe and warm indoors. Not a whole lot different from what some observers here on Earth do!

The other day I was sitting here in front of my computer, flicking idly through the Mars pictures, and I saw a pretty neat one that I thought Mark would enjoy. So, I flicked on the intercom and said to him, “Hey, dear! Have you looked at Mars today?” And then it suddenly struck me just how wonderful and rare that was to say. I can log in to the MER site every day and look at the surface of a planet more than 55 million kilometers away. Most of the time it looks perfectly normal and familiar: rocks, dust, sky, Sun. Except there are a few differences: it’s mostly red, there aren’t any life forms, and there are those pesky little spheres that seem to be scattered all over Opportunity’s landing site. Mysteries among the more familiar-type views of things we recognize.

So, go marvel at Mars. Check out the rocks. Mentally sift through the sand in those dunes. Imagine what it would be like to walk across those dried-up surfaces. And watch the sunset. We’re living in a rare time!

It was about a 3-hour drive to the star party high in the Rocky Mountains. I was one of the invited speakers and was going up to give a talk about observing comets. The idea was that maybe there’d be a couple of talented amateur astronomers who might be interested in chasing comet tail for our team at the University. So, I packed up a trayful of slides, some warm clothes, and a couple of blankets and headed for the hills. The star party site was in a huge meadow reachable by 4-wheel drive, so of course I drove my Mitsubishi Eclipse up there. Got in okay, parked the car and headed for the main tent where they said there’d be a slide projector and screen set up.
I noticed about a dozen or so telescopes set up here and there, and little knots of people standing around each one, most of them watching another one do the scope setup. The sky was absolutely, utterly clear and it was going to be a nice summer night of stargazing. I introduced myself to the star party’s host and he took me over to the slide projector so I could drop the tray onto it. Then we went over and got some dinner. It was the first star party I’d ever lectured at and only the second organized event I had ever attended.
After a burger and some beans and general chat with some of the other attendees, my host decided it was time for me to give my talk. He introduced me as one of the comet researchers from the University of Colorado and turned the mike over to me. I went on for about 30 minutes, showing everybody the kinds of images we were hoping to get from folks like them, and then spent a little while answering questions. By the time I wrapped, it was nice and dark outside and it was time for some stargazing.
The best parts about being a guest speaker at a star party (aside from the free food) is meeting a lot of really nice people and being able to wander around at will doing what I later learned is called “parasitic stargazing.” That’s when you don’t have a scope of your own so you look through everybody else’s. As a guest, I was welcome at everybody’s eyepiece, and that night I saw a lot of cool stuff. By the time I crawled into the back of my car for a snooze around 3 a.m., I’d probably been up and down the summer Milky Way a few times at many different magnifications. It was great!
That star party, called the Rocky Mountain Star Stare, takes place every year. And so do many, many others, at dark sky sites scattered around the world. The year after I visited that one, I began working at Sky & Telescope, and over the next four years I visited star parties every year. I went from Boston to Vermont to Canada, over to Nebraska, out to New Mexico, and down to Pennsylvania a few times, and even took in a star party over in Europe. Each time was great fun, and each time I had the privilege of sharing some great tidbits about Big Astronomy or “Behind the Scenes at Sky & Tel” or other equally interesting topics with thousands of strangers who quickly became friends. And each time I was made welcome at the eyepieces of some really cool telescopes.
There are few better things people can do with their lives than stand out under an open sky with a group of strangers and simply admire the heavens. It’s an amazing experience. And I’ll never forget how much fun it was when I was doing it as part of my job. It was hard to believe I could have that much fun and get paid for doing it!

Our eye on the universe, courtesy NASA and the Apollo 17 astronaut crew.

Our eye on the universe, courtesy NASA and the Apollo 17 astronaut crew.

As you sit in front of the computer reading this, you’re riding along on the largest telescope in the universe (that we know of). Oh, we’re not all sitting on a huge reflecting dish or anything like that. But, we do share surface of the planet with hundreds of observatories. The result is that there isn’t a moment of the day when all parts of the sky in every direction aren’t being studied by a telescope somewhere, somehow. That’s pretty amazing until you stop to think about how many telescopes there are in the world — including all the amateur gear! And, if you rise up a few hundred km into space, we have another whole collection of space-based “eyes on the sky.”

The Big Island of Hawai’i is home to a great collection of observatories, among them the Gemini installation, the Keck Observatory, the James Clerk Maxwell Telescope, the University of Hawaii 2.3-meter telescope, and many others. The National Observatory of Japan has an installation up there with the others on Mauna Kea: the Subaru telescope. I used a couple of their lovely images in my book. Here’s their latest.

Sextans A

Sextans A

It’s the Sextans A galaxy, a dwarf Irregular galaxy — a close neighbor to the Milky Way at only 5 million light years away. Here’s what the Subaru folks have to say about their image:

“Young blue stars and older yellow and red stars shine against a dark sky like jewels in a treasure chest in this image of Sextans A from Subaru Telescope?s prime focus camera Suprime-Cam. Sextans A is a dwarf irregular galaxy belonging to a group of galaxies called the Antlia-Sextans group 5 million light years from Earth. Even though five million light years is quite distant (50 billion billion kilometers or 30 billion billion miles), only about 40 galaxies are closer to our own Milky Way galaxy than Sextans A. The Antlia-Sextans group is the closest neighbor of the Local Group, which includes both our own Milky Way the Andromeda Galaxy.

Irregular galaxies do not have a regular symmetric shape like spiral or elliptical galaxies. Dwarf irregular galaxies containing only 100 million to a billion stars are the most common type of irregular galaxy. One main characteristic of dwarf irregular galaxies, other than their shape, is vigorous ongoing star formation. Sextans A has a mass comparable to only 100 million stars, one thousandth of the Milky Way, but contains a comparatively large amount of gas and dust, the raw ingredients for stars and planets. In the center of Sextans A is a high concentration of neutral hydrogen gas that serves as a reservoir for the formation of new stars. The Suprime-Cam image shows both young stars (blue) old stars (red) near the center of Sextans A where there is a large reservoir of neutral hydrogen gas and star formation is most vigorous. The green color highlights hydrogen gas ionized by radiation (HII regions) from the blue-hot young stars.

Many dwarf irregular galaxies are surrounded by neutral hydrogen gas that extends far beyond where the galaxy?s starlight fades away. Observations with radio telescopes have confirmed that Sextans A is no exception. The origin of this hydrogen gas and its effect on star formation are still unsolved puzzles. Yutaka Komiyama from Subaru Telescope, the observer of Sextans A, is now working on a solution using the Suprime-Cam data.”