The second star system with eight planets, NASA says

The second star system with eight planets, NASA says

This is the only eight-planet solar system found like ours - so far - tying for the most planets observed around a single star.

"The Kepler-90 star system is like a mini version of our solar system", said Andrew Vanderburg, an astronomer at the University of Texas at Austin.

Soaring through space some 137 million km from Earth, it takes an incredible effort to collect data from the telescope. Thanks to the Google Artificial Intelligence, the team was able to look at NASA's data and discover the vast rock.

The researchers trained a computer to learn how to identify exoplanets in the light readings recorded by Kepler - the minuscule change in brightness captured when a planet passed in front of, or transited, a star.

In talking about the two new planets, NASA focused less on Kepler-80g and more on Kepler-90i because it was found to be the eighth planet orbiting the only star in its solar system. According to scientists, the system's outermost planet orbits at a similar distance to Kepler-90 as the Earth does to the Sun.

Kepler-90i is 30 percent larger than Earth and has an average surface temperature believed to be more than 800 degrees Fahrenheit because of its closeness to its star. That means Kepler-90 has as many planets as our solar system, a planet count that hadn't previously been proven to exist outside of our planetary neighborhood.

Image of the Kepler-90 system. "You have small planets inside and big planets outside, but everything is scrunched in much closer", said Vanderburg.

In the Kepler-80 system, they found a sixth planet.

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The research has led to hopes that AI can be used across astronomy to identify new planets and other discoveries with vastly increased speed.

The next three planets beyond Kepler-90i - 90d, 90e and 90f - fall into a sub-Neptune size class and complete an orbit every 60, 92 and 125 days, respectively.

"This is a really exciting discovery, and we consider it to be a successful proof of concept to be using neural networks to identify planets, even in challenging situations where the signals are very weak", said Christopher Shallue, senior software engineer at Google in Mountain View, California.

If you want to search for planets among Kepler's weaker signals - which are far more numerous - then that haystack gets "much, much larger", he added.

Machine learning had not been applied to data acquired by the Kepler telescope until Shallue came up with the idea, he said.

Next up for planet-hunters comes the first-ever space-borne all-sky transit survey, the Transiting Exoplanet Survey Satellite (TESS) space telescope, a two-year survey of over 200,000 stars.

Instead of feeding NASA's neural network cat photos, however, the researchers fed it "15,000 signals" taken from the Kepler data that scientists confirmed were from exoplanets.

"These results demonstrate the enduring value of Kepler's mission", Jessie Dotson, project scientist at NASA's Ames Research Center, said in a statement.