This May, NASA nearly doubled the number of known exoplanets, planets that orbit other stars. Scientists from the Kepler mission announced 1,284 new planets, the largest single batch of planets ever discovered. Of those planets, nine are rocky planets like Earth which could potentially support life. This discovery provides a series of clues to how likely we are to find extraterrestrial life in our galaxy.
Finding New Worlds
According to NASA’s Exoplanet Archive, there are now 3,268 confirmed exoplanets, plus 2,416 unconfirmed exoplanet candidates. Researchers used the “transit method” to discover most of those planets, including the ones just added to the list. The transit method describes how a star’s light appears to dim slightly when something passes between us and the star. When that something is a planet, the light dims periodically when the planet’s orbit brings it in front of the star. It’s like a mosquito flitting past a light bulb: if you look at just the right time, you might see the dark spot. Kepler’s planet discoveries are like noticing the dimming caused by that mosquito from 7 million miles away.
Once astronomers notice the dimming, they need to confirm that it is, in fact, caused by a planet and not something else. In the past, it was a time-consuming and laborious process to upgrade an exoplanet candidate to a confirmed exoplanet: scientists had to confirm each candidate individually, reviewing the exoplanets and their host stars one by one. A steadily increasing rate of exoplanet discovery, however, requires a faster method of review: when new planets can be discovered in bulk, they need to be analyzed in bulk, too.
To confirm Kepler’s latest exoplanet announcement, scientists used a single method of statistical analysis on each candidate. “Planet candidates can be thought of like bread crumbs,” said Timothy Morton, the astronomer who developed this new method. “If you drop a few large crumbs on the floor, you can pick them up one by one. But, if you spill a
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