Telescope spots nearest rocky exoplanet, 'gold mine of science data'

CAMBRIDGE, Mass., July 30 (UPI) -- Scientists at NASA have located the nearest rocky exoplanet, a sphere they say could provide a "gold mine of science data."

The planet, named HD 219134b, orbits a star in the Cassiopeia constellation, near the North Star, that lies roughly 21 light-years from our sun. Though its orbit is too close to its parent star to sustain life, scientists are eager to further analyze the alien world from the ground and air.

Researchers can't actually see the planet directly. Its existence is implied by its shadow-casting orbit through the glow of its sun, which was picked up by NASA's Spitzer Space Telescope. With further study, researchers may be able to measure the chemical makeup of the planet's atmosphere (if it has one) by the way radiation bends around the edges of the rocky world.

"Webb and future large, ground-based observatories are sure to point at it and examine it in detail," Ati Motalebi, a researcher with the Geneva Observatory in Switzerland, said in a press release.

Motalebi is the lead author of a new paper on the discovery, set to be published in the journal Astronomy & Astrophysics.

Like most of the rocky exoplanets discovered by NASA's Kepler mission and other planet-hunting surveys, HD 219134b is a Super Earth -- a rock planet with a mass 4.5 times that of Earth.

The planet's distance from Earth sounds quite far, but not relative to other Super Earths.

"Most of the known planets are hundreds of light-years away. This one is practically a next-door neighbor," said study co-author Lars A. Buchhave, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

The closest known exoplanet, the composition of which remains unknown, is nearly 15 light-years away.