[LINK] On the discovery of Earth-like exoplanet Kepler-452b

[rfmcdonald]

Today's NASA announcement of the discovery of Kepler-452b, a relatively Earth-like planet orbiting the relatively Sun-like yellow dwarf star Kepler-452, 1400 light years away in the constellation of Cygnus, has made headlines. The CBC's coverage is representative.

Kepler 452b, discovered using the planet-hunting Kepler Space Telescope, is about 60 per cent larger than Earth, making it a type of planet called a super-Earth, but scientists think it likely to be rocky, NASA researchers said at a news conference today.

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John Grunsfeld, associate administrator for NASA's science mission directorate in Washington, said the planet appears to be the "closest twin, so to speak, to Earth … that we've found so far."

However, he said it's more like a "close cousin" than an exact twin because of its larger size, which would give it five times the mass of the Earth and double the gravity. But it's less than twice the diameter of Earth, which means it's likely to have a rocky surface. Planets larger than that are not solid, but gassy, like Jupiter.

Planetary geologists and atmospheric scientists think Kepler 452b would have a thicker atmosphere than Earth, with more cloud cover, and is likely to still have very active volcanoes, said Jon Jenkins, Kepler data analysis lead at NASA's Ames Research Center in Moffett Field, Calif.

The star it orbits is the first G2 star — similar to our sun — ever found with a small planet in its habitable zone.

Note that while the planet is broadly Earth-like in its particulars, we know nothing about actual conditions. Most critically, we have no idea what its atmosphere is like, preventing us from knowing if it might support life of some kind.