spacetoday.net: Small exoplanet found around nearby star

Posted: Wed, Apr 22, 2009, 8:55 AM ET (1255 GMT)
Gliese 581 e illustration (ESO)

Astronomers announced Tuesday the discovery of the smallest extrasolar planet yet found, a world less than twice the mass of the Earth just 21 light-years away. The planet, Gliese 581 e, if the fourth planet found around the star Gliese 581, an M-class star 21 light-years away. The planet was found by European astronomers using the radial velocity technique by a European team using an advanced spectrograph at the European Southern Observatory's 3.6-meter telescope in Chile. The planet closely orbits the star, with a period of only 3.15 days, and astronomers said the world is likely a rocky body. They added that another planet in the same system, Gliese 581 d, a world seven times as massive as the Earth in a 67-day orbit, likely was an icy body that migrated in from the other regions of the star system and may now have deep oceans of water.