New planet small but tough

Astronomers confirm the first rocky planet outside the solar system

By Ron Cowen, 15:55 PM January 10, 2011

SEATTLE — A newly discovered planet beyond the solar system is not only the smallest extrasolar planet yet found but also the first confirmed to be made entirely of solid material. Discovered by NASA’s Kepler spacecraft and dubbed Kepler-10b, the body has a diameter only 40 percent larger than Earth’s.

Likely to be partially molten, the planet is too hot to contain liquid water or support life as known on Earth. But the planet’s mass and diameter are known to such high accuracy that the ob...

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