How To Find Our Planet’s Twin
Planet twin Courtesy ESO/M. Kornmesser/Nick Risinger To date, most known extrasolar planets are gas giants like Jupiter or Neptune. Lacking even a solid surface, they are worlds very unlike our own planet. As the search for other Earths continue, a true Earth twin must satisfy five characteristics. 1) Earth size, with a rocky surface... So far, astronomers have found only one planet with a measured size and mass similar to Earth’s: Kepler 78 b, announced last October. A recent study found that most planets smaller than one and a half times Earth’s diameter probably have rocky surfaces. Kepler has found more than 1,000 candidates, but they are not yet confirmed as Earth-like. 2) Near a sunlike star but not too close... One in every five sunlike stars should have Earth-size planets in their habitable zones, according to a new analysis from the University...