Mars in the Crosshairs?

A small asteroid may strike a planet on January 30th — and fortunately Earth isn't the target!

Designated 2007 WD₅, this body was discovered on November 20th by an observing team on Mount Lemmon in Arizona. It loops around the Sun in an elongated orbit that crosses paths with Mars from time to time. For example, in July 2003 it slipped past the Red Planet at a distance of about 2.2 million miles.

But next month's rendezvous has really piqued the interest of celestial dynamicists. Right now the asteroid is predicted to miss Mars by about 55,000 miles, but the odds of an outright collision are about 1 in 75. Currently 2007 WD₅ is a 22nd-magnitude blip in Taurus, and once the bright Moon gets out of the way new observations can be made to refine the asteroid's orbit and trajectory.

Most likely, there'll be another near miss next month. But if a collision does occur, it could raise quite a bit of ruddy dust.

With a diameter somewhere near 150 to 200 feet, 2007 WD₅ would gouge out a crater roughly a mile across — easily visible by any of the three craft now orbiting the planet (NASA's Mars Odyssey and Mars Reconnaissance Orbiter, and ESA's Mars Express).

Since the Red Planet is now near its closest to Earth, the Hubble Space Telescope might have a shot at picking up the splat too. But don't expect to see collisional fireworks if you view Mars through your telescope.

Stay tuned for more exciting details. In the meantime, you can learn a bit more about 2007 WD₅ at the University of Pisa's Near-Earth Objects Dynamic Site.