It doesn't mean all are potentially habitable, but the sheer number of Earth-size planets is a welcome starting point in the search for worlds like our own.
Scientists have yet to find a twin Earth -- one that's not only the right size but also located in the so-called Goldilocks zone, a place that's not too hot and not too cold where water might exist in liquid form.
Two independent groups came up with the new estimate after a fresh analysis of data gathered by NASA's Kepler spacecraft, which was launched in 2009. One team was from the Harvard-Smithsonian Center for Astrophysics; the other from the University of California, Berkeley and University of Hawaii.
More Nation & World Headlines
Divided GOP sees savior in Paul Ryan Navy may challenge Chinese territorial limits Nobel Peace Prize honors groups working to save Tunisia Cracked track blamed for oil train derailment Federal prisons to kick pork off the menu Rumors of affair drove GOP speaker’s race drama 1 dead, 3 wounded in shooting at Northern Arizona University Tunisian democracy group wins Nobel Peace Prize
Our new comment system is not supported in IE 7. Please upgrade your browser here.