A NASA telescope has detected signs of more than 1,200 possible planets outside of our solar system, and dozens of them are in the "habitable zone" around their stars where life might exist.
The Kepler space telescope was launched in 2009 to find planets similar to Earth — rocky, potentially habitable alien worlds. Since then, the telescope has been staring at more than 150,000 stars in one small patch of sky. It's looking for the slight dimming in the brightness of stars that could be caused by a passing planet.
At a news conference, William Borucki, the mission's principal investigator at NASA's Ames Research Center, said that in its first four months of operation, Kepler has found an amazing number of events that could mean a planet is circling a star: 1,235 possible planets.
The amount of dimming reveals the planet's size, and Borucki says these possible planets come in all sizes.
The Kepler space telescope is searching for planets outside of our solar system. But it's just looking at an area that's 1/400 of the sky. See where it's focused.
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"We see 68 Earth-sized, 288 super-Earth-sized, we're seeing 662 Neptune-sized, 165 Jupiter-sized," Borucki said, running down the list.
What's more, 54 of the candidates seem to be located in their star's habitable zone, where temperatures are not too hot and not too cold — meaning there could be liquid water. Five of these potential planets are approximately Earth-sized, with one being smaller than Earth, while four are somewhat larger than Earth.
A planet this size might be rocky — and the thought of a rocky planet in the habitable zone is the kind of thing that thrills planet hunters. It's the kind of place that ET might call home. And larger, Jupiter-like planets in the habitable zone around stars might have moons that could potentially be host to life.
Doing follow-up observations to show that all these dimming events detected by Kepler are truly planets will take time. Now that NASA has released all this data, researchers can get to work.
Debra Fischer, an astronomer at Yale University, called this an incredible, historic moment.
"Kepler has blown the lid off of everything that we know about extrasolar planets," she said. "And this week, to me, feels very different than last week did."
NASA officials point out that in the first 15 years of planet hunting from the ground, scientists had managed to find only about 500 extrasolar planets, mostly big gas balls like Jupiter. So even if not all of Kepler's 1,200 or so possible planets pan out, the orbiting telescope is giving scientists an unprecedented sense of what's out there — and the mission isn't over yet.