First rocky exoplanet is identified

The first Earth-like planet outside the solar system has been identified. Unfortunately, it’s only Earth-like in that it’s solid enough to stand on.

The planet – discovered in February this year – has a mass five times that of Earth, with a radius almost double Earth’s, giving it a similar density. Gliese 581 e, discovered arlier this year is believed to be icy, and most exoplanets are known to be gaseous giants like Jupiter.

“This is science at its thrilling and amazing best,” said team leader Didier Queloz. “We did everything we could to learn what the object discovered by the Corot satellite looks like and we found a unique system.”

The planet, dubbed Corot-7b, orbits a rather unremarkable star, now known as Corot-7. It’s located towards the constellation of Monoceros (the Unicorn) at a distance of about 500 light-years. Slightly smaller and cooler than our sun, Corot-7 is also thought to be younger, with an age of about 1.5 billion years.

The size of the planet was easy to establish – but the initial set of measurements could not provide its mass. However, analysis of data from the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph in Chile gave the answer.

But rocky though it may be, Corot-7b doesn’t look like a nice place to visit.

“Corot-7b is so close [to its star] that the place may well look like Dante’s Inferno, with a probable temperature on its ‘day-face’ above 2,000 degrees and minus 200 degrees on its night face. Theoretical models suggest that the planet may have lava or boiling oceans on its surface. With such extreme conditions this planet is definitively not a place for life to develop,” says Queloz.

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Scientists announce stunning new exoplanet discovery