Originally posted by vorticon
it either hits us or it doesnt and there aint nothing we can do about it. so its not worth worrying about.
Plenty that we can do about potential asteroids that threaten to his the Earth, provided we know about it (which requires better inventory of objects in our solar system), and know about it with enough advanced notice. The further in advance a known threat is dealt with, the less effort is required to deal with it. Solar sails can tug an asteroid out of our way, with enough advanced notice. Even painting the surface of an asteroid can move it using solar pressures, if done a long time in advance. Ion tugs are a more brute force effort, and rockets or mass drivers even more so.
Besides
Apophis - 250-metre-wide - (has a 1 in 45,000 chance of hitting Earth on 13 April 2036), there are a few others that have a good chance of hitting the Earth, or passing close enough to effect their orbit to hit Earth in a follow up orbit.
There are over 108 asteroids, known so far, considered to be "potentially hazardous objects" to planet Earth.
1950 DA - over 1 km across - has a maximum 1-in-300 chance of striking the Earth in the year 2880, and is the most likely threat at this time.
1997 XF11 - about a mile wide (320,000 megatons of dynamite force) - is expected to pass at 30,000 miles in 2028.
asteroid 2000 SG 344 close approach in 2030, and how Earth effect's it's follow up orbits is a concern.
There are others being watched for 2013, 2014, 2016, 2030, 2070, and so forth. Over 108 known threats so far, and this does not take into account asteroids or comets, especially very long period orbiting bodies, we do not know about yet.
