Scientists spot the smallest planet yet found outside our solar system


Astronomers on Wednesday said they had found the smallest planet ever spotted beyond our solar system, a scorched and uninhabitable world tinier than Mercury.

The planet is the innermost of three that orbit a sunlike star called Kepler-37, named after the Kepler telescope, which was launched in 2009 to scrutinize the Milky Way for other worlds.

Kepler monitors more than 150,000 stars, analyzing their light for a characteristic “wobble” caused by the gravitational tug of a planet that passes just in front of the star.

Dubbed Kepler-37b, the little world is a third the size of Earth and just a tad bigger than the moon. It orbits too close to its star to support life. Its surface temperature is an estimated 420 degrees Celsius.

“Kepler-37b is probably rocky with no atmosphere or water, similar to Mercury,” according to the study, headed by Thomas Barclay of NASA’s Ames Research Center. The findings appear in the journal Nature.