Alpha Centauri, a system of three stars, one of whose membersProxima Centauriis the star nearest the sun. Proxima can be seen only with a telescope; the other two stars appear as a single, very bright star to the unaided eye. Alpha Centauri is slightly more than four light-years from the sun. It is in the constellation Centaurus.
Hundred of meteors fly across the sky every night, but only a few make it to Earth. Meteors are best known for the brilliant streaks of light they make as they burn up in the atmosphere. Learn about 10 memorable meteor crashes that left an impression.
On August 24, 2006, the International Astronomical Union (IAU), an organization of professional astronomers, passed two resolutions that collectively revoked Pluto's planetary status.