Most Earth-like extrasolar planet discovered

UC Berkeley planet hunter Geoff Marcy and his colleagues have discovered the most Earth-like extrasolar planet ever seen. (I profiled Marcy a few months ago in ScienceMatters@Berkeley. Link) About 7.5 times as massive as the Earth, the newly-spotted planet is the smallest detected outside our own solar system and likely has a rocky surface. It's 15 light years away and orbits the star Gliese 876. From an article by Robert Sanders, UC Berkeley Media Relations:

"This planet answers an ancient question," said team leader Geoffrey Marcy, professor of astronomy at the University of California, Berkeley. "Over 2,000 years ago, the Greek philosophers Aristotle and Epicurus argued about whether there were other Earth-like planets. Now, for the first time, we have evidence for a rocky planet around a normal star."

Marcy, (Carnegie Institution scientist Paul) Butler, theoretical astronomer Jack Lissauer of NASA/Ames Research Center, and post-doctoral researcher Eugenio J. Rivera of the University of California Observatories/Lick Observatory at UC Santa Cruz presented their findings today (Monday, June 13) during a press conference at the National Science Foundation (NSF) in Arlington, Va.

Part of a system that includes two other Jupiter-size planets, the new rocky planet whips around its star in a mere two days, and is so close to the star's surface that the astronomers say its temperature probably tops 200 to 400 degrees Celsius (400 to 750 degrees Fahrenheit) - oven temperatures far too hot for life as we know it.

Nevertheless, the ability to detect the tiny wobble that the planet induces in the star gives them confidence that they will be able to discover even smaller rocky planets in orbits more hospitable to life.

Link