Mars-Asteroid Smackdown Averted; Astronomers Heave Sighs of Relief

A No-Go Asteroid Collision

Well, it looks like Mars isn’t going to get smacked at the end of this month after all. Astronomers are now giving the asteroid 2007 WD5 a 0.0 percent chance of hitting the planet, based on updated orbital information for the wandering bit of solar system debris. The best guess puts the asteroid on a close fly-by, passing about 7 Mars radii from the surface.Being the bloodthirsty lot we are, some of us at the AAS meeting last week were talking about how “cool” it would be if something DID smack into the surface of Mars, especially while we could watch it with orbiting spacecraft around Mars and the surface-bound rovers. I guess it’s the planetary science equivalent of being a pyromaniac (and watching things blow up).

Planetary Bod Mods

Impacts, which we don’t get to see happen very often, are one of the ways that solar system bodies are modified. Worlds can get smacked into, surfaces can be eroded by weather and other atmospheric processes (like rain and snow (and not just rain and snow made of water, mind you)), they can be paved over by volcanism, or they can be disturbed from below the surface (quakes and subsurface activity driven by internal heat).

Mars has been modified by all these processes over the billions of years it has existed. Take a good look at any picture of Mars, like the one below (taken by the Mars Global Surveyor on August 8, 2006), and you’ll see impact craters, or canyons, or the remains of what look like dry riverbeds tracing their way across the plains.

Every one of those surface features has a story to tell about some aspect of Mars history, and we’re just now decoding what they have to say. So, while I’d have loved to have seen the effect of an asteroid smackdown on Mars, I’m not too upset that it’s missing the planet. There’s plenty of “cool” stuff to study already!

Astronomy News or Celebrity Baby Bumps? You Decide

Cosmic… and Highly Fascinating

Astronomy news can invoke images of weirdness that most people don’t think about in their everyday lives. Colliding gas clouds, superdense neutron stars that might be giant quark balls—there’s no end to the strangeness and wonderfulness of the cosmos.</p>About those colliding gas clouds… it seems there’s a huge mass of hydrogen gas headed toward the Milky Way Galaxy. I heard about it at a paper session on Thursday and it might make the news if some enterprising reporter picks it up and runs with it. Of course, editors being what they are, if this action isn’t related to the election silly-season stories, Britney Spears’s latest antics, Nicole Kidman’s baby bump, or a sports scandal, the story will probably end up at the back of the C section of the newspaper, right before the marriage column. But I digress…When this gas hits, in less than 40 million years, it’ll set off a huge array of stellar fireworks in the region where it collides.

You can breathe a sigh of relief, since this will happen in very distant future, and it won’t hit us directly. This cloud of gas, called “Smith’s Cloud” will hit farther out in the galaxy than the region where we bob along on the galactic currents, and about 90 degrees ahead of us as the galaxy spins. Still, on the odd chance that you’re still around when this happens, look for certain parts of the sky to light up and blaze as the collisions trigger bouts of star formation. Read more about it here.

Speaking of violence in galaxies, the Chandra X-Ray Observatory is taking a look at black holes in galaxy cores, and providing evidence that many supermassive black holes embedded in these hidden regions are spinning extremely rapidly. Now, if you were hanging around the accretion disks that are circling the drain around these black holes, you’d notice that all the stuff in the disk (including, presumably, you) would be getting flung around in orbit around the black hole at close to the speed of light.

And what about that quark ball I mentioned? This morning we had a press conference about a pulsar in a globular cluster. Using Arecibo to measure the timing of the pulsar’s signal, astronomers have been able to determine a pretty good estimate of the mass of the neutron star at the heart of the pulsar. Now, neutron stars are pretty darned massive; they are basically a ball of matter the mass of Earth squeezed into a region of space about 7-14 kilometers wide. Nobody knows what matter is like after it’s been compressed this tightly, but one very educated guess is that it could be a ball of quarks (subatomic particles) glued together. Particle physicists can’t even model this state of matter in an accelerator!

Astronomers using telescopes on Mauna Kea in Hawai’i have found a rare quartet of stars that orbit each other within a region smaller than Jupiter’s orbit around the Sun. Could they have been born in this close proximity? Or, did something else happen to force them to snuggle up together? Check it out.

Planets haven’t been left out of the excitement at this meeting. An astronomer at the University of Texas at Austin has made the first ground-based discovery of an extra-solar planet’s atmosphere, using the Hobby-Eberly Telescope at McDonald Observatory.

Finally, there’s a new radio series on NPR called “Cosmic Radio.” Produced by the National Radio Astronomy Observatory, the series is bringing the history and science of radio astronomy to listeners, in 2.5-minute bite-size lengths. Check out the program’s Web Site for more details.

It’s been a productive and exciting week here in Austin. This “astronomy seminar” is about to come to a close, but for all of us interested in the ongoing research that brings us closer to understanding the cosmos, the story continues…