spacetoday.net: Small exoplanet discovered

Posted: Wed, Jun 4, 2008, 7:34 AM ET (1134 GMT)
Small exoplanet orbiting MOA-2007-BLG-192L (NSF)

Astronomers announced this week that they have discovered the smallest extrasolar planet to date, a world only three times the mass of the Earth. Astronomers used a technical called gravitational microlensing, where the gravity of a passing star, and any orbiting planets, bends light from a background star and causes it to briefly brighten. The planet orbits the star MOA-2007-BLG-192L, a small star that may actually be a brown dwarf about 3,000 light-years from the Earth, and has an estimated mass of three times that of the Earth. Besides proving that nearly Earth-sized planets can be detected, the discovery also demonstrates that planets can form around low-mass stars or brown dwarfs.