Yet another solar system with 8 planets discovered by NASA's AI

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Our efforts to find evidence of planets that could support life have increased exponentially in recent years thanks to the advent of powerful space telescopes such as Kepler.

A record-tying eighth planet has been found in a faraway solar system, matching our own in number.

Shallue, a senior researcher with Google AI, became excited about the prospects for machine learning in space exploration when he realised just how much data Kepler had gathered over the past four years.

Compared with Kepler, TESS will use a similar transit method for observing planets when they pass in front of their parent stars.

The new exoplanets are added to the growing list of known worlds found orbiting other stars. The inner planets have extremely tight orbits with a "year" on Kepler-90i lasting only 14.4 days. The two most distant planets, 90g and 90h, are Jupiter-class gas giants, and take 211 and 332 days to make a round trip.

All of the planets except for 90i were previously known.

As well as the key discovery of Kepler-90i, and other planet called Kepler-80g - an Earth-sized planet - was found in the Kepler-80 system in the constellation of Cygnus.

Scientists think there is a reason the larger planets orbit farther from their sun: It's the cool place to be. "You have small planets inside and big planets outside, but everything is scrunched in much closer", said Andrew Vanderburg, NASA Sagan Postdoctoral Fellow and astronomer at the University of Texas at Austin.

The same phenomenon could be at work here around Kepler-90, scientists said. The structure of the Kepler-90's system hints that the eight planets around Kepler-90 may have formed more spread out, like the planets in our own Solar System, and then somehow migrated to the orbits we see them in today.

The researchers said they aren't sure why the Kepler-90 system has such a crowded field. It could mean that at least some of the planets formed farther out and were eventually drawn inward.

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"Its surface is likely far too hot". But Google Artificial Intelligence - which enables computers to "learn" - looked at archival data obtained by NASA's planet-hunting Kepler telescope and uncovered the eighth planet.

Shallue, a senior software engineer at Google AI, chose to apply a neural network concept to the vast amounts of Kepler data in his spare time.

Vanderburg and Google AI software engineer Christopher Shallue taught a computer to review some 35,000 planetary signals that the Kepler telescope had collected and identify when the transmitted signals had dimmed.

Shallue said Google plans to release all the code needed for someone to join the exoplanet search, using a basic home computer and the publicly available Kepler data.

First, they trained the neural network to identify transiting exoplanets using a set of 15,000 previously vetted signals from the Kepler exoplanet catalogue.

When the scientists finally tested their neural network on signals that it had not seen before, it correctly sorted the planets from the false positives a whopping 96% of the time, Shallue said.

Researchers had known that seven planets were orbiting the star.

"We got lots of false positives of planets, but also potentially more real planets", said Vanderburg.

Case in point: Kepler-90i wasn't the only jewel the AI found.

If the researchers lose track of weaker signals or miss them, they would also be losing the possibility to find new exoplanets. Kepler-80g is an Earth-sized planet that is gravitationally locked in a resonant chain with four of its fellow planets, forcing them to orbit their star nearly as if they were all moving to the music of a highly choreographed dance.