CNN is reporting today that astronomers have determined that there's a one in 75 chance that a big asteroid could hit Mars in January! These may not seem like good odds, but they're astonishingly high considering the amount of empty space in the solar system. Scientifically, it would be an exciting event to witness, assuming that Mars is facing us when it happens.
The asteroid is said to be roughly the size of the asteroid assumed responsible for the Tunguska blast of 1908. For those unfamiliar, a remote area of Siberia was rocked by a massive, 15-megaton explosion in 1908. Compare that with the Hiroshima blast of 13-kilotons, a thousand times weaker! The explosion sparked many theories as to its origin, from the 'mundane' (asteroid impact, comet impact) to the exotic (mini-black hole impact) to the absurd (alien spaceship explosion!). A popular history book came out last year about the blast and the speculation afterwards, The Mystery of the Tunguska Fireball, though I confess I haven't had a chance to read it yet.
Beyond the scientific benefit of such a Mars impact, it could also have a political implications. Good images of a massive impact on Mars might make politicians here on Earth pay more attention to the remote but threatening possibility of catastrophic Earth collisions. Another side benefit: if we felt a little more secure about threats from space, we might be spared more cheesy disaster films in the future.