On the heels of Stephen Hawking and Yuri Milner’s announcement of a $100-million search for extraterrestrial life, NASA has just found the planet that, so far, most closely resembles Earth—and it has the potential to host life.
The Kepler Space Telescope, which has discovered over 4,000 potential exoplanets (1,000 of which are confirmed), recently identified Kepler 452b, a planet 1,400 light-years from Earth, according to the study published in The Astronomical Journal . The planet orbits its sun in 385 days—incredibly close to Earth’s 365-day year. Kepler 452b sits in an ideal “Goldilocks” zone for the creation of life, where temperatures are moderate enough for liquid water.
However, astronomers are skeptical about the possibility of liquid water on Kepler 452b because of its size. The planet’s diameter is 60% larger than Earth’s, so the chances of it having a rocky surface, and therefore containing water, are somewhere between 50 and 62%. If it’s rocky, the planet would have gravity twice as strong as Earth’s, and its mass would be five times as large. In addition, Kepler 452b could have more volcanic activity than Earth. There’s also a chance that the planet could be a large ball of gas, similar to Neptune. But figuring out the composition of Kepler 452b could prove difficult.
Dennis Overbye, writing for The New York Times:
To determine whether Kepler 452b deserves a place on the honor roll of possible home worlds, astronomers have to measure its mass, which requires being close enough to observe the wobbling of the star as it is tugged around by the planet’s gravity. For now that is impossible, as Kepler 452 is 1,400 light-years away.
Kepler 452b is 1.5 billion years older than Earth. Still, it’s considered the most Earth-like planet we’ve ever found. Even if the planet doesn’t host extraterrestrial life, Kepler 452b could provide us with a glimpse of what Earth will be like a billion years from now.
Image Credit: NASA/JPL-Caltech/T. Pyle