Researchers unveiled a total of three planets Thursday, including two potentially livable super-Earths. The discoveries bring the Kepler team closer to its goal.
JPL-Caltech / NASA Ames / Reuters
Kepler is a space-based observatory whose unblinking gaze has rested on some 170,000 stars simultaneously since May 2009.
The three planets are the smallest the observatory has yet detected in stellar habitable zones. These zones represent distances where a planet receives enough light from its host star to harbor liquid water on its surface. Liquid water is essential for the emergence of organic life.
The discoveries bring the Kepler team tantalizingly close to its ultimate goal – to find Earth-mass planets orbiting sun-like stars at Earth-like distances, while also taking a broader census to see how many planetary systems with an Earth-like planet the Milky Way may hold.
Led by William Borucki, a researcher at the National Aeronautic and Space Administration's Ames Research Center near Mountain View, Calif., the team has confirmed 115 extra-solar planets so far, and it has amassed a roster of more than 2,700 planet candidates.
Two of the new planets are part of a five-planet system orbiting a star some 1,200 light-years away in the constellation Lyra. The star, Kepler 62, is about two-thirds the size of the sun and has 70 percent of the sun's mass. It's also about 3 billion years older than the sun.
The system's three inner planets, one comparable in size to Mars, are too close to their sun to be livable. Kepler 62-e, the fourth planet out, however, falls within the habitable zone. Orbiting once every 122 days, the planet is about 60 percent larger than Earth.