NASA’s Kepler Space Telescope mission just made history, announcing the discovery of 1,284 new exoplanets. This is the most new planets announced at one time, with 9 of them considered to be potentially habitable.
“This announcement more than doubles the number of confirmed planets from Kepler,” said Ellen Stofan, chief scientist at NASA Headquarters. “This gives us hope that somewhere out there, around a star much like ours, we can eventually discover another Earth.”
A new technique was utilized to make the discoveries, in which scientists were able to determine the possibility that blips in the data are actually planets, not the result of other astronomical objects.
When looking for exoplanets, Kepler looks at the light coming from distant stars, but if the light dims before it gets to Kepler, it could be a result of a planet passing in front of its sun. This system can lead to false positives, since planets are not the only factor in dimming a star’s light. It could also be a binary star system, a brown dwarf, or a low-mass star.
In the past, confirmation has come in the form of ground-based telescopes — a time-consuming and expensive route. The new technique, however, assesses the likelihood that planet candidates really are planets en masse, without the necessity for follow-up.
“Imagine planet candidates as bread crumbs,” said Timothy Morton from Princeton University in New Jersey, who developed the new technique. “If we drop a few on the ground we can pick them up one by one. But if you spill a whole bucket full of small crumbs, you’re going to need a broom to clean them up.”
The new technique works by first calculating how much the shape of a potential planet’s transit signal looks like an actual planet, and then how common false candidates are out there. These two factors give scientists a reliability score between 0 and 1 for every candidate. Potential planets with a score greater than 99% are referred to as “validated planets,” without follow-up observations taking place.
The point of this mission is to answer a big question: are we the only ones in the Universe?
Kepler scientists can use the transit signal of planets to figure out each candidate’s size and proximity from their sun. This criteria helps determine whether or not they could possibly host life. The nine planets that have been found potentially habitable are less than twice the size of Earth and are positioned in the “Goldilocks zone” of their star, which means they’re not too close or too far, and may even contain liquid water.
And while the verdict is still out as to whether these nine planets can host life, Kepler is almost at the end of its planet-hunting mission, as it is predicted to run out of fuel in about two years. The mission will then be handed to the Transiting Exoplanet Survey Satellite (TESS) and James Webb Space Telescope, who will work together to scan even more stars.
“Before the Kepler space telescope launched, we did not know whether exoplanets were rare or common in the galaxy. Thanks to Kepler and the research community, we now know there could be more planets than stars,” said Paul Hertz, director of the Astrophysics Division at NASA Headquarters. “This knowledge informs the future missions that are needed to take us ever-closer to finding out whether we are alone in the universe.”