NASA’s Kepler Space Telescope has found a lot of planets outside our solar system, but now it may have tracked down a pair that are truly Earth-like.
Scientists recently verified Kepler’s 1,000th planetary discovery, and there are still more to sort through. At a meeting of the American Astronomical Society on Tuesday, researchers announced 554 new candidates found by the telescope, bringing its total to 4,175.
Of those possible planets, eight are in the so-called “Goldilocks zone,” or habitable zone, where the host star is not too cold, not too hot and at just the right distance to keep water liquid.
These findings nearly double the number of known planets in the habitable zone, but researchers are especially excited about two of the exoplanets. Their size, location and star type means they could be rocky planets like Earth — meaning they could have evolved life as we recognize it:
• Kepler-438b, is only 12 percent bigger than Earth in diameter. That means it’s quite likely a rocky planet. Scientists have given it a 70 percent chance of being rocky.
• Kepler-442b is a bit bigger, around 33 percent larger than Earth but still has a 60 percent chance.
What’s important, said SETI Institute astronomer Douglas Caldwell, a study co-author who presented the findings at the American Astronomical Society meeting in Seattle, is that astronomers are a bit closer to finding twins of Earth and answering the age-old question: Are we alone?
“These planets do exist; we didn’t know that before,” said Guillermo Torres, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. “What we’re really looking for is signs of life eventually. We’re not there yet. It will take many years, but this is the first step.”
But while 438b hits the sweet spot in size, 442b has it beat when it comes to distance from the sun. Both orbit a small red dwarf star, cooler than Earth’s Sun, but they also orbit more closely. 438b gets 40 percent more light than Earth, which means it has around a 70 percent chance of being able to hold liquid water. But with 66 percent as much light as our own planet, 442b has a 97 percent chance of being in the habitable zone.
So neither planet is a sure shot, but they’re more promising than anything else Kepler has ever found.
“We are now closer than we’ve ever been to finding a twin for the Earth around another star,” NASA scientist Fergal Mullally said. He and his colleagues hope to use their similarities to — and differences from — Earth to learn something about the formation of the planet.
The Associated Press contributed to this report.
