The final frontier just got a little bigger.
Scientists from Google and the University of Texas announced yesterday that they used NASA data and artificial intelligence to identify a new exoplanet in the Kepler-90 system. The discovery of Kepler-90i is notable because it’s the eighth planet circling the Kepler-90 star. That makes Kepler-90 the only solar system besides our own that has eight planets orbiting a single star.
The research was led by Google software engineer Christopher Shallue and UT Austin postdoctoral fellow and astronomer Andrew Vanderburg. They fed public data on exoplanets (planets beyond our solar system) from NASA’s Kepler Space Telescope into a computer.
“There’s so much data humans can’t look through it,” Vanderburg told Observer. “So if humans can’t, what about a machine?”
Kepler’s four years of data focused on light curves, or the minuscule changes in brightness when a planet passes in front of a star.
The duo did their machine learning research independently of NASA, but the agency offered them assistance and answered questions. Using the same neural network (or computer brain) system employed in Facebook’s translation software and Apple’s FaceID system, they trained the AI to classify planet signals and detect patterns using 15,000 signals from the Kepler catalogue.
To make the AI’s job easier, researchers limited the search for new planets to systems (like Kepler-90) that already featured more than one planet orbiting a star. There are 670 such systems in outer space, with thousands of signals in each. Not all of them denote planets, but the program was able to detect these false positives with 96 percent accuracy.
Kepler-90i was the first real planet discovered by the AI. The hot, rocky mass orbits the Kepler-90 star (which is about 2,545 light-years from Earth) every 14.4 days. The planet, which is 30 percent larger than Earth, has little potential for human life—it’s so close to the star that the average surface temperature exceeds 800 degrees Fahrenheit.
Kepler-90 is more compact than other systems: the planet farthest from the star is roughly the same distance from it as Earth (the third planet in our solar system) is from the Sun.
The neural network also discovered one other planet, Kepler-80g. This marks the sixth planet in the Kepler-80 system. The discovery is notable because five planets in the system (including Kepler-80g) form a resonant chain. Planets configured in this way are locked together by their mutual gravity. The phenomenon is quite rare—there are only a handful of resonant chains in the whole solar system.
Shallue and Vanderburg’s paper detailing their findings will be published in The Astronomical Journal. They plan to follow up these discoveries by using AI to examine the entire Kepler system, which is comprised of 150,000 stars. They hope to find more planets with orbits and sizes similar to Earth.
“We consider this result to be proof of concept that we can use AI and neural networks to find signals in Kepler data,” Vanderburg said.
AI can also be applied to other areas of space exploration, such as discovering gravitational waves.
“We’re really just scratching the surface of what we can do with this exciting new technology,” Vanderburg said. “It’ll be a big benefit.”