Eric Agol has identified Kepler 62f, a small and probably rocky planet orbiting a sun-like star in the Lyra constellation, a university release reported Thursday.
The planet is about 1.4 times the size of Earth, receives about half as much solar heat and radiation as Earth and orbits its star in a "year" equivalent to 267.3 Earth days, he said.
It's one of two planets orbiting in the star Kepler 62's habitable zone, the right distance from the star to potentially allow liquid water to exist on a planet's surface, which could suggest conditions amenable to life.
Kepler 62f and its companion, Kepler 62e, are the smallest exoplanets found so far in a host star's habitable zone.
"The planets this small that we have found until now have been very close to their stars and much too hot to be possibly habitable," Agol said. "This is the first one Kepler has found in the habitable zone that satisfies this small size."
"Kepler 62f is the smallest size and the most promising distance from its star, which by these measures makes it the most similar exoplanet to Earth that has been found by [the] Kepler [telescope]."
"This type of discovery is the reason we launched the Kepler spacecraft -- to find small, Earth-sized, potentially Earth-temperature planets," Agol said. "At the same time, though, it isn't exactly the same as Earth. It is slightly larger and cooler than Earth.
"It tells me how special the Earth is and how it may take some time -- hopefully not too long -- to find its exact twin."