Earth-like Planet Confirmed
Dec. 14, 2011
The Kepler space telescope has found the first confirmed Earth-like planet orbiting in the “habitable zone” of a distant star. The planet, named Kepler 22b, is about 2 ½ times as large as Earth. The habitable zone, also called the Goldilocks zone, is the region around a star that scientists believe is neither too hot nor too cold to support life as we know it. In this zone, the temperature is cool enough to let liquid water form and warm enough to prevent water from freezing. Earth orbits in the habitable zone of the solar system. Kepler’s sole mission, since the spacecraft’s launch in 2009, has been to spot planets circling distant stars.
Since the first extrasolar planet was discovered in the mid-1990′s, scientists have uncovered thousands of planets orbiting stars other than the sun. Because larger objects are easier to spot, most of the planets discovered so far are giants, many times larger than Jupiter, the largest planet in the solar system. Scientists have no way of knowing at this point if Kepler 22b has life. They think it is more likely that the planet is rocky, like Earth, rather than gaseous, like Neptune. It could even be an ocean world. They have calculated that if the planet has an atmosphere, the temperature there could be a pleasant 72 °F (22 °C).
The discovery comes just as the Allen Telescope Array (ATA) operated by the SETI Institute is back in operation. The 42 telescopes in the ATA, which were shut down early in 2011 because of budgetary problems, scan the sky for radio signals that could be signals from extraterrestrial beings. Over the next two years, SETI plans to focus the ATA at the top 1,000 habitable planets found by Kepler.
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