Update from January 9:
Since our last update, we have received numerous tracking measurements of asteroid 2007 WD5 from four different observatories. These new data have led to a significant reduction in the position uncertainties during the asteroid's close approach to Mars on Jan. 30, 2008. As a result, the impact probability has dropped dramatically, to approximately 0.01% or 1 in 10,000 odds, effectively ruling out the possible collision with Mars.
Astronomers first observed asteroid 2007 WD5 in November 2007. The asteroid’s trajectory is expected to place it within 30,000 miles of Mars January 30, 2008 — and possibly place the asteroid on a collision course with the Red Planet. The odds of the asteroid striking Mars have ranged from 1 in 350, up to 1 in 25.
On January 2, NASA provided this update:
With new observations taken December 29, December 31, and January 2 by the Magdalena Ridge Observatory in New Mexico, scientists at NASA’s Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, California, have updated their trajectory estimates for the asteroid. Based on this latest analysis, the odds for the asteroid impacting Mars on January 30 are now about 1 in 28, or 3.6 percent.
Asteroid 2007 WD5 measures about 160 feet (50 meters) across. If it strikes Mars, the energy will be similar to the 1908 Tunguska blast in Siberia. When an asteroid exploded over the taiga, the blast scarred trees over 810 square miles (2,100 square km).
Don’t fix your backyard scope on Mars January 30.You won’t be able to spy this unlikely event. Still, have you tried to observe Mars with its close proximity to Earth this winter?