Astronomers have conclusive evidence that a planet spotted in a star system 500 light years away is rocky and solid, just like Earth.
Scientists have long figured that if life begins on a planet, it needs a solid surface to rest on, so finding one elsewhere is a big deal. "We basically live on a rock ourselves," said co-discoverer Artie Hartzes.... "It's as close to something like the Earth that we've found so far. It's just a little too close to its sun" [AP].
Yes, for while the exoplanet, Corot-7b, is rocky like Earth and is only about five times more massive than our home planet, it's hardly our twin. Its close proximity to its star means that it completes an orbit (its "year") in just 20 hours, and the climate extremes are punishing.
Temperatures soar above 2,000 degrees on its day side and sink to minus 200 degrees on the night side. It means the surface could be covered with molten lava or boiling oceans and it certainly could not hold any form of life as we know it [Scientific American].
Corot-7b was first discovered in 2008 using the space-based COROT observatory, and its existence was announced last February. At that time researchers already believed that the planet was rocky, but it took 70 more hours of observations to get firm measurements of the planet's mass and size, which allowed researchers to calculate its density. Those calculations proved that Corot-7b isn't a gas planet, like so many of the other exoplanets discovered to date; instead it must be rocky. The new findings were presented at the ongoing European Planetary Science Congress. Planetary scientist Alan Boss, who wasn't involved in the research, says that finding this rocky planet
gives scientists more confidence that they'll find more Earth-like planets farther away, where the conditions could be more favorable to life.... "The evidence is becoming overwhelming that we live in a crowded universe," Boss said [AP].
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