“Super Earth” With Atmosphere Discovered

The search for planets that could have life on them got a boost yesterday when astronomers announced the discovery of the first “Super Earth” planet with an atmosphere.

The planet is only slightly bigger than ours and is water-based.  It orbits a red-dwarf star according to a report in “Nature.”

“The discovery itself is very exciting,” says team leader David Charbonneau of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. “But what it says about looking for signs of life on other planets is even more exciting.”

The discovery raises hopes that we may find other such planetary bodies with atmospheres in the near future.

The planet, called GJ1214 b, orbits the red dwarf GJ1214 once every 1.6 days, which raises its atmospheric temperature to at least 250 degrees Fahrenheit. The star resides 42 light-years from Earth (about 247 trillion miles), close by astronomical standards.

Though GJ1214 b is 6.6 times heavier and 2.7 times wider than Earth, our iron-cored world is 21/2 times denser, which suggests the new discovery is made of water squeezed to high pressure by the planet’s high gravity. “It probably has an extraordinarily deep ocean,” astronomer Geoff Marcy of the University of California at Berkely says in a commentary accompanying the report.

The find comes as international teams this week detected two more “Super Earth” planets orbiting sun-like stars, one orbiting the star 23 Lib and the other circling 61 Virginis. Both of the planets, at least 7.5 and 5.3 times heavier than Earth, respectively, turned up in telescope searches that look for gravitational wobbles induced on stars by planets.

Charbonneau’s team, however, is tracking about 2,000 red-dwarf stars, dim stars 40% to 8% the size of the sun, by looking for dips in starlight caused by planetary eclipses. The team uses eight amateur telescopes distributed worldwide. After only two months of tracking a few hundred stars last year, the team found a 52-minute starlight dip comes every 1.6 days from GJ1214, which gives away the planet’s orbit.

The team is requesting a Hubble telescope analysis of the planet’s atmosphere, possible because of its proximity. “To look for life elsewhere, we really have to look for the chemical signatures, like oxygen, that life would inevitably imprint on the atmosphere,” Charbonneau says.