Two new Earth-sized exoplanets discovered
Hunting for habitable worlds, NASA’s Kepler space telescope has unveiled two new planets, some 950 light-years away, that are the smallest yet detected, and the closest in size to Earth. In a paper published this week in Nature, scientists from MIT and elsewhere report that the planets — one just about Earth’s size, and the other a bit smaller — likely have rocky compositions, similar to Earth, and orbit a star much like the sun. But that’s where the similarities end. Compared with Earth’s leisurely 365-day orbit, the new planets practically whiz around their star in a matter of days or weeks. Their tight circuits, closer even than Mercury’s orbit around our sun, make the planets extremely hot — likely too hot to sustain life. While either planet is far from Earth’s twin, scientists say the discovery is a technological milestone.“For the Kepler space telescope, it’s extremely significant, because it...