Christopher Shallue's??? AI only needed to look at 670 stars before spotting the new planets, which had eluded detection by human astronomers. As it starts to study the hundreds of billions of stars in our galaxy it is likely to discover many more new worlds.

At a news conference on Friday morning local time, NASA revealed the existence of the two new planets.

One of them, Kepler-90i, a scorched rocky world 2545 light-years from Earth, is the eighth planet spotted in the Kepler 90 system. That ties it with our own solar system for the most known planets orbiting a star.

The other, Kepler-80g, is an Earth-sized world in the Kepler-80 system.

The planets were found by Mr Shallue's AI as it trawled through data generated by NASA's planet-hunting Kepler Space Telescope.

Mr Shallue, who trained at Monash University, works as an AI researcher with Google in California. The type of AIs he builds are called neural networks, which are designed to simulate the human brain and excel at picking out patterns in data.

Kepler generates a lot of data. Previously, to spot a planet, astronomers had to manually sift through it, looking for telltale dips in brightness as a planet passes in front of a distant star.

"I read Kepler had generated so much data that humans were not able to sort the dataset themselves. As soon as I read that my ears pricked up," says Mr Shallue.

"Any time you have way too much data for humans to analyse, this is a great space to apply machine learning."

So he Googled planet-hunting scientists and cold-emailed one, outlining his idea.

A year later, his method is being hailed as the future of astronomy.

"The torrent of data from new telescopes being built ... will overwhelm us. We can only explore it using AI", says Swinburne University astronomer Associate Professor Alan Duffy.

"I'm happy for Google to take this job. By eye, trying to spot this type of pattern, I shudder to think how many years it would take."

Until a decade ago, we thought planets were rare. But now astronomers believe that nearly every star in the sky has at least one.

Mr Shallue's AI has only looked at about 670 stars. Kepler's database contains 150,000, and it seems certain many more worlds will be spotted.

What that all means, says Dr Duffy, is the odds of us being alone in the universe have lurched lower again.

"This latest discovery just reinforces that our solar system is not that special.

"The potential locations for life continue to increase, and the things that make us special are becoming more commonplace.

"You'd have to really be a betting man to bet against alien life being out there, with so many worlds that could potentially harbour it."