2010 RF12 and another small asteroid that passed close to earth Wednesday were detected three days before their fly-by, illustrating the improving capability of asteroid-spotting telescopes.
For years scientists had a hard time figuring out which asteroids the meteorites came from.
Halley's Comet and other named comets may have formed around other stars in the galaxy, but were snatched into orbit around the sun back when it was packed with hundreds of other stars.
The most detailed images yet of Pluto, taken by the Hubble Telescope, reveal a yellow-black sphere whose surface appears to be among the most dynamic in the solar system.
Cassini flyby reveals water vapor in plume from Enceladus. A hidden ocean on Titan?