Maunder Crater on Mars (photo credit:NASA)
Mars Asteroid! An asteroid named 2007 WD5 is to have a 1-in-75 chance of hitting Mars, the fourth planet from the sun in our solar system, on January 30, 2008.
If the asteroid with a length of an Olympic-size swimming pool (about 160 feet across) does hit the red planet, the impact of 2007 WD5, which travels at a speed of 28,000 mph, with Mars, will blast a crater half-a-mile wide, said Steve Chesley, a member of NASA's Near Earth Object office at JPL in Pasadena.
"Because scientists have never observed an asteroid impact -- the closest thing being the 1994 collision of comet Shoemaker-Levy with Jupiter -- such a collision on Mars would produce a 'scientific bonanza." Chesley told to the LAT.
The asteroid which was traced only since November is about the size of one that exploded over Siberia in the Tunguska event of 1908 [wiki]. The force of that explosion, the equivalent of 10 million to 20 million tons of TNT, turned hundreds of square miles of forest into a flattened expanse of scorched logs. The left image is a computer-generated picture showing a 3D reconstruction of Lake Cheko [wiki] which scientists from University of Bologna in Italy claimed to be the crater left by Tunguska event.
Update: The possibility of Mars asteroid collision on January 30 is now very low, a January 9 update on the Near-Earth Object Program at the NASA's Jet Propulsion Laboratory said the impact probability is approximately 0.01% or 1 in 10,000 odds.
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.
Our best estimate now is that 2007 WD5 will pass about 26,000 km from the planet's center (about 7 Mars radii from the surface) at around 12:00 UTC (4:00 am PST) on Jan. 30th. With 99.7% confidence, the pass should be no closer than 4000 km from the surface.
Impact craters are routinely scattered on the surface of moon, but not on the Earth. Meteor Crater in Arizona is one of the best known examples of an impact crater on Earth. The crater is 1.2 kilometers in diameter and 200 meters deep. It formed approximately 49,000 years ago when an iron meteorite that was roughly the size of a school bus struck the Arizona desert east of what is now Flagstaff (via).
Picture of Meteor Crater in Arizona (by David Roddy, USGS)
Another famous meteror crater on the Earth is Mexico's Chicxulub Meteror Crater on Yutachan peninsular, which was formed when a large asteroid/comet struck the Earth 65 million years ago and believed to be responsible for the die-out of Dinosaurs during the Cretaceous mass extinction. The following two pictures show the Chicxulub crater (via) and its location (via).