The Kepler Space Telescope may be mostly retired these days, but it is still shedding light on the farthest reaches of the universe. Now, NASA has announced that researchers have identified 1,284 new exoplanets—more than doubling the number of faraway planets that scientists previously confirmed.
Kepler was launched into orbit in 2009 and for the next several years it focused on a single point in the sky. During that time, the space telescope was gathering data from 120,000 stars, with scientists on the ground hoping to spot the shadows of distant planets as they passed across their suns (much like the transit of Mercury earlier this week). But while scientists have spotted hundreds of exoplanets in Kepler’s data since it started scanning the skies, this discovery marks the largest number of exoplanets ever reported at the same time, Loren Grush reports for The Verge.
"When the Kepler space telescope launched, we did not know whether exoplanets were rare or common in the galaxy," Paul Hertz, director of NASA Headquarters’ Astrophysics Division, said in a press conference earlier today. "Thanks to Kepler, we now know that exoplanets are common, and that a reasonable fraction of the stars in our galaxy has potentially habitable planets. Knowing this is the first step toward addressing the question of are we alone in the universe."
Using a new statistical technique, scientists were able to quickly analyze data gathered by the Kepler Space Telescope and sort through the many candidates for newly discovered exoplanets. Previously, scientists had to sort through every possible planetary candidate Kepler tagged and analyze it on a case-by-case basis, Maddie Stone reports for Gizmodo. However, the statistical models devised by Princeton University mathematician Timothy Morton helped scientists pick out possible false positives in the thousands of candidates, allowing them to narrow and focus their search.
"Planet candidates can be thought of like bread crumbs,” Morton says in a statement. “If you drop a few large crumbs on the floor, you can pick them up one by one. But, if you spill a whole bag of tiny crumbs, you're going to need a broom," he says. "This statistical analysis is our broom."
This discovery is just the beginning. Those 1,284 exoplanets announced today are just the candidates that scientists are 99 percent sure are planets. According to NASA’s calculations, the space telescope discovered another 1,327 candidates that are very likely to be exoplanets, but fell just shy of the 99 percent certainty scientists require to label something an exoplanet. Extrapolating these calculations, some NASA researchers say that there could be tens of billions of potential planets scattered throughout the Milky Way alone, Paul Rincon reports for the BBC.
"They say not to count our chickens before they're hatched, but that's exactly what these results allow us to do based on probabilities that each egg (candidate) will hatch into a chick (bona fide planet)," Natalie Batalha, the Kepler mission scientist at NASA's Ames Research Center says in a release. “This work will help Kepler reach its full potential by yielding a deeper understanding of the number of stars that harbor potentially habitable, Earth-size planets—a number that's needed to design future missions to search for habitable environments and living worlds.”
Next up: figuring out what the exoplanets are made of. In 2018, NASA will launch Kepler’s successor, the James Webb Space Telescope. The most powerful space telescope ever constructed, the James Webb should be able to determine the composition of these distant planets’ atmospheres by measuring how much light passes through them. In the meantime, researchers working on the Kepler data hope to finish cataloging its finds by October.