NASA’s Kepler Space Telescope announced the discovery Wednesday (Feb. 26) of 715 new exoplanets orbiting around 305 stars, according to the space agency’s news release. The find brings the total number of alien worlds to about 1,700 and nearly doubles the number known to humanity.
“We’ve hit the motherlode; we’ve got a veritable exoplanet bonanza,” said Kepler co-leader Jack Lissauer of NASA’s Ames Research Center in Moffett Field, Calif.
Only four of the newly discovered planets orbit their stars in “habitable zones,” that region of space that’s neither too close to their sun, where it’s too hot for life to develop, nor too far away, where it’s too cold.
The four planets are all bigger than Earth, but smaller than Neptune, so at this point no one knows if their atmospheres are suitable for life as we know it.
Many of the planets orbit in what astronomers now recognize as a “typical” solar system, in which the largest planet orbits further from the star while several smaller, Earth-size planets orbit closer in.
“These new Kepler results are very helpful in filling out the statistics of solar systems,” said Adam Burrows of Princeton University, according to National Geographic. “The goal is to see how typical is our own solar system, and ones unlike it.” Burrows was not part of the team.
Kepler is able to identify planets by looking at the dip in light as they pass in front of their parent stars. Called “transits,” they can be seen only for planets traveling in orbits that are viewable edge-on to Earth, which happens about 10 percent of the time, National Geographic says.
Using a “validation through multiplicity” technique described in an upcoming issue of Astrophysical Journal, the scientists were able to use the gravitational interactions of planets in their solar systems to rule out false identifications.
Even though the Kepler mission was badly hurt last year because of a broken gyroscopic wheel, there are still reams of data for scientists to analyze and the mission is still operating, though at a much reduced level.
Now NASA is looking ahead to a new Kepler 2 mission, which may be able to detect 100 new planets every year, according to team member Jason Rowe of the SETI Institute in Mountain View, Calif.