Saturday, February 25, 2006

An email about black holes

While preparing to use the telescope yesterday, I received the following question from a reader:

I think that if you can go through a black hole without getting ripped apart, you would be spit out of a white hole in a new universe. Please email me back and tell me if that is a good thought.

This is quite an interesting thought; unfortunately, I cannot give a very definitive response. However, I'll do my best to ramble on some about it.

The trick with black holes is that we do not and cannot know what is going on inside the black hole's event horizon, or the point at which gravity is so strong that light cannot escape. At some point deep inside the black hole, the laws of physics as we know them must break down. So what does that mean?

Some people have suggested, like you, that the center of a black hole (also called a singularity) may open a tear in the fabric of space and time, creating a wormhole to other parts of the universe, or perhaps other universes. The main problem with this idea is that we don't yet have a good theory for this and can't test the idea. We don't know if other universes may exist, or if it is even possible to find out. So we have left the bounds of science and entered into pure speculation.

The only firm thing I can say is that, to date, no astronomer has ever found a "white hole," or an object spewing out matter. This doesn't mean that they don't exist, but they must be rare if we haven't found them yet.

Friday, February 24, 2006

Observing in Chile

I survived my trip to the southern hemisphere, where it is currently the dog days of late summer. The weather is warm, the sun is shinng by day, and the night sky is gorgeous. This sure beats the last time I was here, when it was snowy and an icy wind was howling.

So, why do I travel all the way to South America to use the telescope, when there are several in Arizona? The main reason is that we can see different stars down here than back in the United States. From Chile I can see the Southern Cross and the Large and Small Magellenic Clouds, two of the closest galaxies to our own. And, many of the very distant galaxies I am looking at could not be observed from Arizona. But we have things in our sky that are not easily seen from Chile. The North Star and the Big Dipper are never visible, and many famous galaxies like the Whirlpool Galaxy are also not visible.

On Sunday I leave Chile for Hawaii, where I get to spend two nights using the world's largest telescope, the Keck Telescope. I'll be sure to let you know if I make any fascinating discoveries!

Wednesday, February 22, 2006

Up, up and away!

I am currently sitting in the Dallas airport, waiting for a flight to Santiago and a two night observing run at the Magellan Clay Telescope at Las Campanas Observatory. Due to the travel, my blogging will likely be off and on for the next few days.

Tuesday, February 21, 2006

No life on Venus?

It should come as little surprise, but a scientific panel has concluded that the Earth is in no danger from Venusian germs riding back to Earth and harming Earth-based life.

Venus is a hellish place. The average temperature is nearly 750 degrees Celsius (roughly 1350 degrees Fahrenheit) -- hot enough to melt tin, lead, aluminum, zinc, and plutonium, among other things! Venus's clouds are made of sulfuric acid. It is not surprising that we don't expect to find anything living there!

So, why spend money on a study? As we begin to explore the planets around us (notably Mars), there is a tiny, tiny chance that we could find life, and that this life could prove harmful to life on Earth. The cost of repairing any damage from that mistake is many times more than the costs of studies to show how to prevent that problem. Also, by beginning with worlds where there is almost certainly no life, scientists have many chances to avoid overlooking some potential danger. For example, there are parts of Venus's atmosphere where conditions are not quite so inhospitable. Could there be germs floating aroung the clouds there? This is very, very unlikely. But it reminds us to worry about germs that may be floating around the atmosphere in Mars -- so even if astronauts just fly over Mars in an airplane, we know to worry about their safety and possible contamination.

Monday, February 20, 2006

Where E.T. Calls Home

If you had to look for alien planets, where would you look? The galaxy has one hundred billion stars -- if you could look at one every second, it would take 3200 years to search them all. The problem is, NASA is planning a planet search mission called the Terrestrial Planet Finder. This series of satellites will need much more than one second per star, and may only get to look at a few thousand stars during its lifetime. So, which thousand should we look at?

A report by astronomer Margaret Turnbull lists nearly 150 stars that might be worth checking out. The stars on this list are chosen to be nearby (within 100 light-years of Earth) and to be fairly similar to the sun -- old stars with about the same amount of metals as the sun, about the same temperature and mass as the sun, and without any companion stars.

It makes sense to start the search for Earth-like planets with Sun-like stars. After all, all four known rocky planets are around our Sun! So we know that Sun-like stars can have Earth-like planets. Maybe other stars can have Earth-like planets, too, but it is a riskier proposition.

Since the mission launch is not for at least ten years, this list will be debated, revised and expanded until launch. But perhaps in ten years we'll know where E.T. calls home.

Wednesday, February 15, 2006

Spitzer ist Spitze!

If my rusty German isn't failing me, the headline means approximately "Spitzer is the tops!"

The Spitzer Space Telescope is a telescope launched in August 2003. It is slowly drifting away from Earth (on purpose!) and taking cool pictures of the Universe in infrared light.

Currently, my office mates are busy writing proposals to use this telescope over the next year. A telescope proposal is a tricky thing to write, especially for a telescope like Spitzer or the Hubble, where many more people want to use the telescope than time is available. Only once a year can scientists propose to use these telescopes, so you have to think ahead and try and make your science sound more interesting than the next person's science.

So, for the past few weeks, my friends have been pouring over lists of interesting targets, trying to calculate exactly how much time they would need to get their desired science complete. The deadline is tomorrow at 1pm local time, and I suspect that they will not get much sleep tonight. Today I've been trying to stay out of their hair as much as possible.

I can relax this time. The science I am currently doing doesn't gain a lot of knowledge from the infrared light, so it is not a good use of my time to write such a proposal. But I'll keep my fingers crossed for my friends' projects!

Tuesday, February 14, 2006

Celestial Valentines

The human brain excels at pattern recognition. This is what allows us to make a face out of dark and light patches on the moon, to find butterflies in ink blots, or to see bunny rabbits in the clouds.

In memory of the martyring of St. Valentine, below are some pictures of hearts mankind has found in the heavens. Click on each picture to go to a web page with more information. Happy Valentine's Day!


A heart on Mars seen by the Mars Global Surveyor


ANOTHER heart on Mars from the Mars Global Surveyor


The Heart Nebula, IC 1805

Monday, February 13, 2006

See a nova!

If you are up nice and early in the morning, why not try and find a nova with your naked eye? All you need is a dark sky, a view of the east, a lot of patience, and some star maps. An article on the nova can be found at Sky and Telescope.

A "nova" is a thermonuclear explosion on the surface of a white dwarf. "Huh?" you say? Okay. Let's back up a bit.

White dwarfs are the "ashes" of a dead star. A star burns all of its fuel, changing it from hydrogen into helium and then on into carbon and oxygen. All that is left is a glowing ember abouth the size of the Earth.

Many stars have companion stars. If the two stars are close enough, the gravity of the white dwarf can pull some gas from the surface of the companion star onto its own surface. After enough gas has built up, it gets hot enough to start fusion, and BOOM! Just like a hydrogen bomb, the gas rapidly ignites, fuses into helium, and creates an explosion.

While these explosions are big, they are MUCH smaller than supernovae, in which an entire star is ripped apart by a powerful explosion. In novae, the white dwarf survives. After the explosion settles down, it begins to steal more gas from the neighboring star, and the cycle starts again.

The currently-visible nova (with the exciting name RS Ophiuchui), last was visible in 1985, and before that in 1967.

Thursday, February 09, 2006

Your tax dollars (not) at work

SOFIA, the Stratospheric Observatory For Infrared Astronomy is an ambitious project. This is an infrared telescope mounted in a modified Boeing 747 airplane. It has been under construction for several years and cost nearly $600 million, but it is finally about finished.

Infrared light, or what most of us would call "heat," allows astronomers to look through clouds of dust in our galaxy, exploring star birth that has been invisible. Infrared light also allows astronomers to look for evidence of planets around other stars. The problem is that most infrared light from space does not reach Earth's surface. So in order to see infrared objects, astronomers need to get above much of the atmosphere. That can be done with satellites, like the Spitzer Space Telescope, or with airplanes.

So, after a lot of time and money, SOFIA is just about ready to fly. So why has NASA zeroed out the budget starting in 2007? Without (promised) money, SOFIA will not be able to operate, and $600 million of equipment, not to mention a world-class telescope, will sit in storage, doing nobody any good. Yes, SOFIA has had problems and cost overruns. And yes, money is tight. But it seems wasteful not to try.

SOFIA is not dead yet; it will have a performance review soon and could easily see its funding restored. Let's hope all goes well!

Monday, February 06, 2006

Astronomy-inspired art

A fellow postdoc, Michael Cushing, is giving this week's colloquium on his research, brown dwarfs. Brown dwarfs are "failed stars," stars that do not have enough mass to keep nuclear fusion going in their cores.

One interesting fact about low-mass stars (red dwarfs) and brown dwarfs is that they are all about the same size as the planet Jupiter. This is due to a property of matter at very high pressures, like you find at the centers of these planets/stars called "degeneracy."

This neat fact inspired the following two artistic renditions comparing our sun, a red dwarf, two brown dwarfs, and the planet Jupiter. This art is from Dr. Robert Hunt at the Infrared Processing and Analysis Center in Pasadena, CA.

The first picture is what each of these objects look like in optical light. From left to right, we see the Sun, a red dwarf, a hot brown dwarf, a cool brown dwarf, and Jupiter. Jupiter is only visible due to light reflected from the sun, while the brown dwarfs glow feebly due to heat left over from their formation. The red dwarf and the sun produce their own light by nuclear fusion in their cores.

Click here to see the image

The second picture is what these objects look like in infrared light. In the infrared, even Jupiter glows due to heat left over from its formation five billion years ago. The sun is blue because it is "hot" for an infrared object. The red dwarf and hot brown dwarf are colored yellowish because they emit most of their light in the infrared, like our yellow sun emits most of its light in the optical. The cool brown dwarf is blue but hard to see, because most of its infrared light is absorbed by methane gas in its atmosphere. Finally, Jupiter is a rainbow of colors, as it has lots of different chemicals and clouds that have their own unique infrared characteristics.

Click here to see the image

Quiet day

It was a quiet weekend here in Lake Wobegon, my home town...

Sorry, my mind was wandering. I am in Tucson, AZ, which is not my hometown. But it was still a quiet weekend, and I have little to talk about this morning. So, I though I'd just leave a picture I came across:

It's everyone's favorite, the Orion Nebula, as imaged by the Hubble Space Telescope. The Orion Nebula is a stellar nusery, where thousands of young stars have just been born, and many more are still forming, hidden behind copious amounts of dust and gas. Clicking on the picture will take you to a web site with discussions about the image, the science behind it, and lots of versions of this picture.

Thursday, February 02, 2006

That's Right Wood Chuck Chuckers, It's GROUNDHOG DAY!

For those of you who weren't aware, today is Groundhog Day. Bright and early this morning, Punxsutawney Phil saw his shadow, meaning six more weeks of winter. According to the Punxsutawney Groundhog Club, Phil is correct "100%" of the time.

As long as Phil sees his shadow, he's bound to be correct 100% of the time, because today marks six weeks until the spring equinox, the first day of spring. Groundhog day is a cross-quarter day, a day located halfway between an equinox and a solstice. Each season is 13 weeks long, meaning the Groundhog Day cross-quarter day occurs six-and-a-half weeks after the Winter Solstice (first day of winter) and six-and-a-half weeks before the Spring Equinox.

Enjoy your six remaining weeks of winter!

Wednesday, February 01, 2006

Journal Club

Today I gave one of two lunchtime talks for Steward Obervatory's weekly Journal Club.

Journal Club is fairly common among astronomy institutions. It consist of a student or faculty member talking about a paper that has been published in one of our journals. Sometimes the paper is a obviously an important development in a certain field. Sometimes it has some neat pictures to look at. And some times the paper is poorly written and fun to talk about.

Today I spoke about a paper that was not overly important, but contained a mysterious result. Some collaborators of mine looked at some cool white dwarfs (the remains of dead stars) with the Spitzer Space Telescope, and found that many of them are fainter than expected in infrared light. The really interesting thing is, there is no good explanation for this faintness!

So, I learned something cool, I got to talk to my colleagues about it, and I learned some tricks for PowerPoint. Not too bad for a half-day's work!