Gaming Journal: Extra-Solar Super Earth

Extrasolar 'Super Earth' is First to have an Atmosphere

By Dan Vergano
USA TODAY

Astronomers Wednesday reported the discovery of the first known "Super Earth" with an atmosphere, a water world orbiting a nearby red-dwarf star.
The detection of the planet only a bit larger than Earth, reported in the journal Nature, raises hopes of upcoming star surveys spotting another planet like ours.

"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 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-Berkeley says in a commentary accompanying the report.

"This discovery helps to make the case that inner (Earth-like) planets are likely to have water and hence to be habitable by life as we know it," says planetary scientist Alan Boss of the Carnegie Institution of Washington (D.C.).

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.