Friday, December 23, 2005

Signing off for the year

With the holidays here, I am off travelling until the start of the New Year. So until then, best wishes to everyone.

Early next year many exciting astronomy events are going to happen -- the launch of a probe to Pluto, the return of pieces of a comet to Earth, and a large meeting of the American Astronomical Society. So stay tuned for exciting news in 2006!

Tuesday, December 20, 2005

New Horizons launch on the horizon

Of the nine planets in the Solar System (Okay, maybe there are ten. But since no official decision has been made by the Powers That Be, I'll stick to nine), only one has not been visited by a robotic probe, and that is Pluto. That will soon change, however.

Earlier this week, the New Horizons spacecraft was moved to a launch pad in Florida, preparing for a launch in late January. Despite the large rocket being used to launch this relatively lightweight (1000 pound) probe and despite a gravitational boost from Jupiter, the probe will still take 10 years to reach Pluto! And this probe will be racing along, taking only eight hours to pass the moon on its way out -- the Apollo moon missions took three days to cover that distance!

The New Horizons probe will also study at least one other of the strange Kuiper Belt objects, trying to figure out exactly where these big balls of ice formed in the early Solar System.

So, stay tuned for news of the launch, and then settle back and wait ten years to see a close-up view of Pluto!

Thursday, December 15, 2005

Practice makes perfect!

Last night I spent several hours at Kitt Peak learning how to use a new camera built by Ed Olszewski, an astronomer at Steward Observatory. This camera is on Steward's 90-inch Bok Telescope. This camera is huge by astronomy standards -- over a one-degree field-of-view. In other words, four full moons could fit in a single picture!

I will be using this camera for the first time on New Year's Day as part of an ambitious new survey my collaborators and I are doing. So, we figured we had better go up to learn how to use the camera. Each astronomy camera is different, with its own strengths and weaknesses. And since telescope time is precious, we donn't want to waste our own time trying to learn how to use the camera and then using it wrongly.

Last night, astronomer Richard Cool was kind enough to take time out of his work on the camera to teach my colleagues and I how to use it. We learned a lot, and I think we'll be able to make good use of the telescope now! We probably will struggle some our first night trying to remember everything, but as time goes on we will get better and more efficient.

Just like playing a musical instrument requires a patient teacher, time to practice, and just as you can expect mistakes when you first start playing, using an astronomical instrument requires a patient teacher and lots of hands-on use, with a few missteps along the way.

Wednesday, December 14, 2005

The Christmas Star

This time of year, a popular question astronomers get asked is, "What was the Star of Bethlehem?" This blog normally steers clear of religious issues altogether. After all, (1) I am an astronomer, not a theologian, (2) I would hope that this blog can reach to any person, regardless of their beliefs, and (3) my beliefs are just that -- mine -- and not necessarily yours. But, since the question comes up and since the Star of Bethlehem is central to many people's celebrations this time of year, I thought I would at least touch on the issue.

The fact is that astronomers have no good explanation for the Star of Bethlehem as described in the Gospel of Matthew. Different ideas have been put forth: a conjunction of the planets Mars, Jupiter and/or Saturn in 7/6 B.C., a comet, a supernova, and even more exotic astronomical phenomena. A search for "Star of Bethlehem explanation" on Google or your favorite search engine will being up a plethora of pages with highly-variable quality of scholarly explanations for each of these. In spite of this, none of the proposed explanations fit all of the passages from the Bible. Perhaps in the years between the Nativity and the writing of the Gospels the event became a little garbled or exaggerated, or perhaps the narrative was invented, or perhaps there is no physical explanation for what appeared in the sky.

So, I have no definitive answer to what the "Star of Bethlehem" might have been, and anybody who claims to know a definitive physical explanation is probably overstating their case. If you are interested in this, I would suggest that you read some of the materials on the web or elsewhere and form your own opinion. Like many religious matters, the Star of Bethlehem must remain an issue of faith, not of science.

Tuesday, December 13, 2005

Back in the swing of things

It took a week, but I think I am finally over my "telescope lag" (or "astral temporal disruption fatigue," as a friend suggested) and back on a pretty normal day schedule. These long nights are very difficult to work through. But I did get some fabulous images at the telescope, leaving me with lots of work to do for the coming months!

Now I must get ready for our January national astronomy conference, the winter meeting of the American Astronomical Society. Over a thousand astronomers from across North America (and some from the rest of the world) will be converging on Washington, D.C. for a grand meeting. I will be giving a short talk myself on my research. I only have five minutes to talk, so I have to boil down months of work into just a few paragraphs. I also hope to have a job interview or two there!

Wednesday, December 07, 2005

Last night!

It has been a long few weeks, but tonight is my last night of observing for the year of 2005. (I start up again on January 1!) I always have mixed feelings at the end of an observing run. I am always quite happy to go back home and get back to a typical routine. But there is always more data I wish I had been able to collect. I guess that gives me something to do for next year.

Most of my night at the telescope is spent waiting for exposures to finish. We open the shutter on the camera for ten minutes to half an hour, and then sit back and wait for it to finish. What I do while waiting depends quite a bit on the camera I am using. For taking pictures, like tonight, I just do a quick check to make sure the image quality is okay (and figure out what is wrong if the quality isn't high); otherwise I wait to work on the images when I get back to Tucson.

If I am taking spectra (splitting the light up into its component colors), I need to work on the data to figure out if the object we are looking at is "interesting." Of course, the definition of "interesting" depends on what we want to do. For instance, when I am looking for white dwarfs (the remains of dead stars), we find a lot of quasars (bright black holes halfway across the universe). Although quasars are quite cool objects, we aren't looking for them, so we move on to another object. If the star is a white dwarf, though, we need to stay and take more observations. Clear as mud? Probably.

Monday, December 05, 2005

A pretty picture

Last night was a gorgeous night on Kitt Peak. In the corner of one of the pictures we took at the end of the night, we spotted this galaxy, much bigger and brighter than the "faint fuzzies" we were looking at. This galaxy is NGC 3079, a spiral galaxy in the constellation Ursa Major (the "Big Dipper"). It is located about 50 million light-years away; the galaxies I am looking at for my work are about 3 billion light-years away.

NGC 3079 has also been looked at by the Hubble Space Telescope, as seen in this picture. Why is the Hubble picture much more colorful than mine? Two major reasons -- Hubble has graphics artists to help them bring out the colors, while yours truly has limited artistic ability, and the Hubble Telescope took pictures in more colors than I did (I stuck to red, green and blue).

This galaxy is also known as a "starburst" galaxy. Lots of stars are being formed very quickly, mostly hidden from view by thick clouds of dust. This galaxy also has a large black hole at its center that is gobbling down lots of the gas and dust in the galaxy.

It's been a hard day's night

I should be sleeping like a log! From sunset to sunrise tonight is thirteen and a half hours. For the astronomer, that is a long workday, especially to do five nights in a row. Ugh!

But, here on top of Kitt Peak, we have been working hard all night and getting some good data. It has been a crystal clear night with very steady skies.

I haven't had the time to put together a pretty picture yet, but I should have one tomorrow.

Saturday, December 03, 2005

From one telescope to another

Well, I "survived" a rather pleasant trip to use the Keck I Telescope on the Big Island of Hawaii. have since returned to Arizona and driven up to Kitt Peak, a telescope about 60 miles west of Tucson. I'm already worn out, and I still have four nights to go!

At the Keck Observatory, I was looking for white dwarfs, the remains of stars that have run out of nuclear fuel. These dwarfs are a lot like the glowing embers in a dying fire -- they are hot from the heat of the nuclear engine of the parent star, but they make no new energy. So, like the embers of a fire, white dwarfs slowly cool off, getting fainter and fainter. My fellow scientists and I are using this property to figure out how old the white dwarfs are. By finding the faintest white dwarfs in a group of stars, we have a pretty good idea how old those stars are!

Anyway, we found lots of white dwarfs during our stay, including some that are very mysterious -- they look different than most of the white dwarfs we found. Now I just have to figure out what that means!

Here at Kitt Peak, I'm looking at something completely different -- I'm looking at groups of galaxies far, far away. Where the white dwarfs above are all "only" 3000 light-years from Earth, these galaxies are a few billion light-years a way! With a little clear weather, I'll try to get a picture up within the next day or two.