From: Richard A. Kerr, ScienceNOW
Published April 22, 2009 08:08 AM

Closing In on the Next Earth

A group of astronomers today announced the discovery of the least massive planet yet detected outside of our solar system. It is lightweight enough--between two and three times the mass of Earth--to almost certainly be rocky like Earth rather than a huge ball of gas. Although the planet orbits too close to its star to be habitable, a new analysis of one of its neighbors suggests a world with deep oceans. All this raises the prospect of discovering an Earth-size planet orbiting at just the right distance from its star to give life a chance. "It's just a matter of time now," says exoplanet specialist Sara Seager of the Massachusetts Institute of Technology in Cambridge.

Planet hunters are an ambitious lot. They're after an Earth-sized, rocky planet orbiting at a comfortable, livable distance from its star. For ease of observation, the exoplanet should periodically pass between the star and astronomers on Earth. They've already bagged huge planets orbiting in a star's habitable zone--where any water would be liquid--and huge planets transiting in front of their stars. They've found small planets too: CoRoT-Exo-7b, whose discovery was announced in February, is twice the diameter of Earth but likely eight times its mass--and far from habitable.

ADVERTISEMENT

What makes the new world so noteworthy is its small mass. At the Joint European and National Astronomy Meeting being held this week in Hatfield, U.K., a 13-member group led by planet hunter Michel Mayor of the Observatory of Geneva in Switzerland announced that Gliese 581 e, located only 20.5 light-years away in the constellation Libra, is so small that it isn't smothered with gas the way Jupiter or Neptune is.

Article continues

Terms of Use | Privacy Policy

2014©. Copyright Environmental News Network