Artificial Intelligence Helps Nail 8-Planet Solar System Like Our Own

With the discovery of an eighth planet, the Kepler-90 system is the first to tie with our solar system in number of planets.
NASA/Wendy Stenzel

Every time we think we’re in a class by ourselves, it’s only a matter of time. Used to be our solar system had the most planets around a single star. But thanks to new data from NASA’s Kepler spacecraft, we’re now tied with the Kepler-90 system, a sun-like star 2,545 light years away in the constellation Draco.

Researchers recently uncovered Kepler-90i, a sizzling-hot 8th planet that orbits Kepler-90 once every 14.4 days. To find it, they used a unique method: machine learning. Machine learning is a type of computer science that gives machines (computers) the ability to go beyond strict programming and learn on their own. In this case, computers learned to identify planets by finding instances in the Kepler data where the telescope recorded signals from exoplanets beyond our solar system.

Both the solar system and the Kepler 90 system have an equal number of planets; the layout is also the same with the smaller planets closer to the host star and bigger ones further away. But Kepler-90’s planets are scrunched up much closer to their host star compared to our more roomy solar system. The outermost planet, Kepler-90h, orbits at the same distance from its sun as Earth does from ours. The narrow orange ring is the orbit of the new planet, Kepler-90i. NASA

“Just as we expected, there are exciting discoveries lurking in our archived Kepler data, waiting for the right tool or technology to unearth them,” said Paul Hertz, director of NASA’s Astrophysics Division in Washington in a press release.

The discovery came about after researchers trained a computer to learn how to identify exoplanets in the light readings recorded by Kepler – the tiny change in brightness captured when a planet passed in front of, or transited, a star (see below). Inspired by the way neurons connect in the human brain, this artificial “neural network” sifted through Kepler data and found weak transit signals from a previously-missed eighth planet orbiting Kepler-90.

Kepler finds planets around other stars by measuring periodic dips in the star’s brightness as a planet (in silhouette) passes in front of it. The graph at right shows the before, during and after effects as a planet transits in front of its host sun. NASA

About 30% larger than Earth, Kepler-90i is so close to its star that its average surface temperature may exceed 800°F (426° C), on par with Mercury and Venus and likely too hot to support life.

Kepler-90 is a 14th magnitude star in Draco near the border with Cygnus, a.k.a. the Northern Cross. Stellarium

“The Kepler-90 star system is like a mini version of our solar system. You have small planets inside and big planets outside, but everything is scrunched in much closer,” said Vanderburg, an astronomer at the University of Texas at Austin.

Kepler’s four years of data consists of 35,000 possible planetary signals. Previously, automated tests, and sometimes human eyes, are used to verify the most promising signals in the data, but the weakest signals often are missed. Researchers Christopher Shallue and Andrew Vanderburg thought there could be more exoplanet discoveries faintly lurking in the data.

Newly discovered Kepler 90i lies close to its host sun; its surface bakes at around 800°F (426°C), as hot as Venus and probably very unfriendly to life. NASA

First, they trained the neural network to identify transiting exoplanets by feeding it 15,000 previously studied signals from the Kepler exoplanet catalogue. In the test set, the network correctly identified true planets and false positives 96% of the time. Once the neural network “learned” to detect the pattern of a transiting exoplanet, the researchers directed their model to search for weaker signals in 670 star systems that already had multiple known planets. Their assumption was that multiple-planet systems would be the best places to look for more exoplanets.

“We got lots of false positives of planets, but also potentially more real planets,” said Vanderburg. “It’s like sifting through rocks to find jewels. If you have a finer sieve then you will catch more rocks but you might catch more jewels, as well.”

We’re teaching our machines rudimentary thinking … and it’s starting to show results.

Shallue and Vanderburg plan to apply their neural network to Kepler’s full set of more than 150,000 stars. Here’s their research paper

If you could be there, Kepler-90 and its planets might look a little like this artist’s rendering. NASA

2 Responses

  1. TMcGrath

    More “fake news” by an ignorant media. There is no such thing as “Artificial Intelligence.” Even the paper referred to in the story never uses the term “Artificial Intelligence.” Obviously “AstroBob” has utterly no clue what he is talking about, but that is to be expected when it comes to these self-proclaimed “journalists.”

    1. astrobob

      Artificial intelligence or AI is a very real thing. You can look it up — along with neural networks. It’s just another way of using computers in new ways to help find essential information that might otherwise be overlooked in terabytes of data. It’s so easy to throw the derisive term “fake news” around, but this is certainly not that.

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