The composition of comet Hartley 2 suggests that comets might have been a bigger source of Earth's water than previously thought. It's also challenging models of solar system formation.
Researchers calculated the orbits of 40,000 low-mass M-dwarf stars and found 18 that may come dangerously close to our cosmic neighborhood in the next billion years. While the chances of this actually happening are probably slim, researchers said, the results could be dramatic.
Meteor shower August 2010 peak comes early Friday. Emanating from the constellation Perseid, the meteor shower could yield sightings in some locations of up to 75 meteors an hour.