Kepler-90i is the eighth planet to be found in the Kepler-90 system, which is 2,545 light years away from Earth. “This discovery ties Kepler-90 with our own solar system for having the most known planets," according to NASA's Paul Hertz, who spoke in a press conference.
The rocky planet is about 30% larger than Earth, likely has an average temperature of about 800°F, and orbits its star every 14.4 days. All of the known planets in the Kepler-90 system are closer to their star than Earth is to the Sun, says astronomer and co-discoverer Andrew Vanderburg from the University of Texas at Austin.
A second Earth-sized planet, Kepler-80g, was also spotted.
Exoplanets can be found by looking for a change in a star's brightness as a planet passes in front of it. The AI — a neural network — learned to identify planets from 15,000 Kepler signals that had already been labeled by scientists. When the AI then looked at data from 670 stars, it found the two planets.
What's next: They hope to study Kepler's data from more than 150,000 stars to see if they can spot weak signals researchers missed.