NASA Confirms Discovery of First Earth-Sized Planet in Habitable Zone of its Star

Posted on April 17, 2014

p class="first">NASA has confirmed the discovery of the first Earth-sized planet in the habitable zone of its star. News of the planet's discovery first broke in March at the Search for Life Beyond the Solar System conference. NASA notes that planets have previously been found in the habitable zone, but they are all at least 40% bigger than Earth. This planet, Kepler-186f, is less than 10% larger than Earth in size. However, the mass and composition of the planet are not known.

NASA says, "If you could stand on the surface of Kepler-186f, the brightness of its star at high noon would appear as bright as our sun is about an hour before sunset on Earth."

Paul Hertz, NASA's Astrophysics Division director at the agency's headquarters in Washington, says in the announcement, "The discovery of Kepler-186f is a significant step toward finding worlds like our planet Earth. Future NASA missions, like the Transiting Exoplanet Survey Satellite and the James Webb Space Telescope, will discover the nearest rocky exoplanets and determine their composition and atmospheric conditions, continuing humankind's quest to find truly Earth-like worlds."

Kepler-186f is located in the Kepler-186 system, which is about 500 light-years from Earth in the constellation Cygnus. Its star is an M dwarf or red dwarf. Kepler-186f orbits the star once every 130 days. It gets about 1/3 of its energy from the star that Earth gets from the sun. The planet has four companion planets, Kepler-186b, Kepler-186c, Kepler-186d and Kepler-186e. The image below shows the Kepler-186 system and compares it our solar system. You can view a larger version of the image here.

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