Since being launched into space in March 2009, NASA's Kepler spacecraft has been searching the Milky Way for planets that might sustain liquid water. Named after the German astronomer who discovered planetary motion, the craft has turned up nearly 3,000 such candidates, each of them positioned in the habitable zone of the Sun-like stars they orbit. But few of them have been so excitedly announced as two planets Kepler recently turned up, nicknamed Kepler-62e, Kepler-62f, and Kepler-69c, all of which are significantly larger than Earth and orbit stars a bit smaller than the Sun. During a press conference held at a NASA observatory in northern California on Thursday afternoon, the agency said that astronomers believe each planet may contain liquid water. (One of them, Kepler-62e, may in fact be completely covered in water.)
The astronomers came across the planets using a sophisticated telescope attached to the Kepler spacecraft, which records planets as they pass in between the spacecraft and a star. The telescope records the amount of light blocked by the planet, a measurement astronomers use to determine the planet's size. Later, after comparing data collected by telescopes positioned on the Earth's surface, astronomers can pinpoint the movement and location of those planets, relative to nearby stars. Using this technique, NASA has confirmed more that more than 120 planets in the Milky Way occupy a habitable zone.
We're still far off from knowing what any of these planets actually contain, though. "Scientists do not know whether life could exist on the newfound planets, but their discovery signals we are another step closer to finding a world similar to Earth around a star like our sun," a NASA statement indicated.