It's the largest number of worlds ever discovered in a planetary system outside our own.

The star known as Kepler-90, is just a bit hotter and larger than the Sun; astronomers already knew of seven planets around it.

The newly discovered world is small enough to be rocky, according to scientists.

"This makes Kepler-90 the first star to host as many planets as our own Solar System," said Christopher Shallue, a software engineer at Google, which contributed to the discovery.

The discovery was based on observations gathered by Nasa's Kepler Space Telescope.

Its parent star is very distant, lying 2,545 light-years away. But its planetary system appears to be ordered in a similar way to our own.

Andrew Vanderburg, a co-discoverer at the University of Texas at Austin, said: "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."

To give a sense of how close, the outermost planet in the system orbits at around the same distance the Earth does from the Sun.

Because the new world, dubbed Kepler-90i, is so much further in - it completes one circuit of its star every 14.4 days - it's estimated to have a scorching hot surface temperature of around 425C.

The machine learning technique was also used to find a new Earth-sized planet, called Kepler 80g, around a different star.

Some 3,500 exoplanets - worlds circling other stars - have been documented in recent decades.

Fuentes: BBC