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NASA's Kepler discovers Earth-sized world in a star's habitable zone

Artist concept of Kepler-186f
Artist concept of Kepler-186f

NASA announced on Thursday that the Kepler Space Telescope has discovered the first Earth sized planet orbiting in the habitable zone of its star, The new planet has been designated Kepler-186f. While its size and distance from its star is known, its mass and composition are not. But scientists speculate that it is a rocky world, much like Earth, and possibly has water. The planet and its four companions were detected by measuring changes in the brightness of the star as they passed between it and the Kepler.

Its star, Kepler-186, is about 500 light years away from Earth in the Constellation Cygnus. The star is about half the size and mass of our sun. It is classified as a m class red dwarf, which describes roughly 70 percent of the stars in the Milky Way Galaxy.

Even though Kepler-186f is the size of Earth and is in the habitable zone of its star, the area where liquid water is possible, it does not mean that it contains life. They will depend on a number of factors, including what sort of atmosphere if any it has and whether or not it has water. But is a prime candidate for a planet that does contain life, perhaps even as we know it.

Kepler has discovered hundreds of planets, mostly gas giants the size of Jupiter or greater. However some have been what have been described as “super Earths” or rocky worlds as much as half again the size of Earth. A few of these have been detected orbiting their stars habitable zones and thus may contain life.

The upcoming James Webb Space Telescope will be able to examine Kepler-186f and other worlds that Kepler has discovered in greater detail, determining their compositions and atmospheric conditions. Kepler will also discover other Earth-like worlds. The JWST is scheduled for launch in 2018.