New discovery pushes star Kepler-90’s menagerie to eight planets

NASA machine-learning venture with Google digs up two new exoplanets.

This is one of two new exoplanets scraped from the massive archive of data from the Kepler space telescope by NASA’s Andrew Vanderburg and Christopher Shallue of the Google AI team. Planets detected by Kepler show up as slight dips in the brightness of a star—the result of the planet passing in front and blocking some of the light. Some planets are more obvious than others, and the goal here was to turn the algorithm loose on digging through past measurements for weak signals that had been missed.

Like all machine learning systems, this one was fed measurements from previously identified exoplanets to work out what differentiates real signals from coincidental blips. The researchers say the system emerged with the ability to correctly identify false positives about 96 percent of the time.

It was then fed the data for 670 stars that have had at least one planet identified already in the hopes that more would turn up. A handful did, but after eliminating the ones that could potentially be explained by confounding factors like interactions with companion stars, two candidates passed all the standard screening steps.

One appears to be a rocky planet only about 30 percent larger than the Earth that becomes the 8th planet discovered orbiting a Sun-like star, designated Kepler-90, which is 2,545 lightyears away. Sporting a dizzying orbit of just 14.4 days, this planet is close enough to its host star to be at least 435 degrees Celsius (about 800 degrees Fahrenheit)—decidedly “hot porridge” in Goldilocks parlance. In fact, all eight planets in this star system would fit inside Earth’s orbit.

The other new exoplanet orbits Kepler-80, which is about half as far away. Although it has a very similar orbital period of 14.6 days, it should be a few hundred degrees cooler (though still over the boiling point of water) and even closer to the size of the Earth. The newly discovered planet brings the total in the Kepler-80 family to six, five of which are locked into resonant orbits.

With some success demonstrated, Vanderburg and Shallue intend to feed the rest of Kepler’s data into the system to see what else they can find.

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