NASA’s Kepler Mission Confirms Its First Planet in Habitable Zone of Sun-like Star
NASA’s Kepler project on Monday has confirmed the discovery of a small earth like planet 600 light-years away from Earth in the “habitable zone” of a star not unlike our own sun. NASA’s Kepler space telescope, which was named after 17th-century German astronomer Johannes Kepler, focused to discover and identify Earth-like planets orbiting other stars. It is launched on March 7, 2009 and has a minimum expected mission lifetime of 3.5 years. Kepler also has discovered more than 1,000 new planet candidates, nearly doubling its previously known count. Ten of these candidates are near-Earth-size and orbit in the habitable zone of their host star. Candidates require follow-up observations to verify they are actual planets.
The newly confirmed planet, Kepler-22b, is the smallest yet found to orbit in the middle of the habitable zone of a star similar to our sun. The planet is about 2.4 times the radius of Earth. Scientists don’t yet know if Kepler-22b has a predominantly rocky, gaseous or liquid composition, but its discovery is a step closer to finding Earth-like planets. Till now Kepler has identified 2,326 planet candidates. Of these, 207 are approximately Earth-size, 680 are super Earth-size, 1,181 are Neptune-size, 203 are Jupiter-size and 55 are larger than Jupiter.
Kepler-22b is located 600 light-years away. While the planet is larger than Earth, its orbit of 290 days around a sun-like star resembles that of our world. The planet’s host star belongs to the same class as our sun, called G-type, although it is slightly smaller and cooler. Of the 54 habitable zone planet candidates reported in February 2011, Kepler-22b is the first to be confirmed. This discovery will be published in upcoming The Astrophysical Journal.