Asteroids torn apart by Earth 21
douglips writes "BBC News has a story about near-Earth Asteroids being broken up by Earth's tidal forces. The binary asteroid systems are studied to learn the density of the bodies, which is just the sort of thing you need to know if you want to nudge one out of a collision course with Earth."
asteroid light curves (Score:4, Informative)
As a further comment, the existence of double impact craters is not necessarily suggestive of binary asteroid systems -- an asteroid is more likely to break apart when it actually enters the Earth's atmosphere than in more distant encounters, so it's probably not good to assume that the system had already broken up and become a binary during a previous encounter.