‘Godzilla of Earths’: Alien Planet 17 Times Heavier Than Our World Discovered

 Named Kepler-10c, the planet is 17 times more massive than our planet, and has been named a ‘mega-Earth’.

Astronomers didn’t believe such a world could exist because they believed anything so large would grab hydrogen gas as it grew and become a gaseous ‘mini-Neptune’.

A new kind of ‘Godzilla’ planet – dubbed a mega-Earth – has been discovered in a distant star system. Pictured is an artist’s impression of the newly discovered planet, which dominates the foreground. Its sibling, the lava world Kepler-10b, is in the background

But to their surprise, Kepler-10c has been able to remain solid despite being more than twice as old as the Earth.

The discovery suggests that potentially life-bearing rocky planets may be far more common than first thought, and some could be extremely ancient.The Kepler-10 star system is thought to be 11 billion years old, meaning it formed less than three billion years after the birth to the universe.

‘This is the Godzilla of Earths. But unlike the movie monster, Kepler-10c has positive implications for life,’ said Dr Dimitar Sasselov, from the Harvard Smithsonian Centre for Astrophysics (CFA).

‘Finding Kepler-10c tells us that rocky planets could form much earlier than we thought. And if you can make rocks, you can make life.’

Kepler- 10c isn’t likely to harbour life as it is too close to its parents star. Gravity at the surface is about twice that of Earth’s gravity.

The planet circles its sun-like parent star, located in the constellation Draco, every 45 days.

It has at least one unusual neighbour, Kepler-10b – a scorching hot ‘lava world’ three times heavier than Earth that whips around the star once every 20 hours.

The planet was originally spotted by Nasa’s Kepler spacecraft, which finds planets using the transit method – looking for a star that dims when a planet passes in front of it.

By measuring the amount of dimming, astronomers can calculate the planet’s physical size.

Kepler-10c, which has a diameter more than twice that of the Earth, was previously thought to fall into the category of ‘mini-Neptune’ planets that have an icy core surrounded by a thick gassy envelope.

But observations made from the Italian Galileo National Telescope in the Canary Islands confirmed that it has 17 times the mass of the Earth – far heavier than expected.

This proved it must be made from dense rocks, like the Earth.

‘We were very surprised when we realised what we had found,’ said astronomer Dr Xavier Dumusque, also from the Harvard-Smithsonian Center for Astrophysics, who led the research.