Even though the Kepler mission has found 3,601 candidate planets, only 246 had been previously confirmed. That’s because it takes a lot of extra, painstaking work to ensure that the dips in light that Kepler picks up really are from a planet and not a false positive, such as a binary system of two stars that regularly block each other’s light.
The new method researchers used to find and confirm these 715 planets relies on the idea that planets seem to cluster in systems with other planets, rather like our own.
“Multiplicity is not random,” Lissauer said, calling it “a powerful technique for wholesale planet verification.”
Two teams of researchers were able to devise a probability-based method that focused on these multi-planet systems, making the largest single exoplanet haul since the first one was discovered in the 1990s. It nearly quadruples the number of confirmed planets found with Kepler (from 246 to 961) and doubles the overall number of confirmed planets to about 1,700. (Many exoplanets have also been discovered using another technique called the radial velocity method, which looks for the gravitational influence of a planet on its star.)
“I’m super excited about this,” said Sara Seager, a planetary scientist at the Massachusetts Institute of Technology who was not involved in the work. The multi-planet systems will help scientists understand our own solar system’s development, she said. For example, many of these systems seem to have multiple planets clustered in an orbit smaller than Venus, or even Mercury. Why are our own solar system’s inner members relatively spaced out?
The findings will also shed light on strange planets like mini-Neptunes, which have no analog in our own solar system, and sharpen scientists’ search for Earth-sized, potentially Earth-like planets, scientists said.
“Nature wants to make small planets,” Seager said.