Those three planets bring Kepler’s Earth-like planet count to a total of eight. In order to qualify as “Earth-like,” these exoplanets must be less than twice the size of the Earth and orbit their own sun within the habitable zone. This “Goldilocks zone” is a belt in solar systems where it’s neither too hot nor too cold for liquid water to exist.
“Each result from the planet-hunting Kepler mission’s treasure trove of data takes us another step closer to answering the question of whether we are alone in the Universe,” said John Grunsfeld, associate administrator of NASA’s Science Mission Directorate at the agency’s headquarters in Washington. “The Kepler team and its science community continue to produce impressive results with the data from this venerable explorer.”
The Kepler team has also found super-Earths and gas giants like Jupiter around other stars. NASA artists compiled retro-style travel posters from three discovered planets.
Kepler finds planets by watching distant stars for fluctuation in light. If the light hitting the telescope drops dramatically and then returns to normal levels, chances are a planet came in between the star and Kepler. Scientists can analyze the data and light filtered by the candidate planet’s atmosphere to make guesses at the size, mass and composition.
“With each new discovery of these small, possibly rocky worlds, our confidence strengthens in the determination of the true frequency of planets like Earth,” said co-author Doug Caldwell, SETI Institute Kepler scientist at NASA’s Ames Research Center at Moffett Field, California. “The day is on the horizon when we’ll know how common temperate, rocky planets like Earth are.”
The space telescope actually has two crippled stabilizing gyros. But instead of giving up on the mission, engineers are using pressure from photons emitted by the sun to stabilize the telescope. The first space telescope looking for alien worlds is literally balancing on a sunbeam to continue its mission, and that’s not science fiction, that’s science fact.
Citizen scientists can also participate in the mission. The website PlanetHunters.org contains catalogs of data from K1, the original Kepler mission, and K2, the extended mission making use of the sun to balance the telescope. The K2 data has been sorted through, but Planet Hunters still needs help sifting through the K1 data.
The website’s instructions read:
“As the planet passes in front of (or transits) a star, it blocks out a small amount of the star’s light, making the star appear a little bit dimmer. You’re looking for points on the light curve that appear lower than the rest. When you spot a potential transit, mark each one on the light curve.”