New planet discovered: 'Mega earth' is twice as old as Earth and 17 times bigger


A new planet believed to be twice as old as Earth has been discovered in a distant star system, dubbed a "mega-Earth" by astronomers.

The rocky heavyweight planet is up to 17 times bigger than Earth, and according to theory, it should have evolved over time into a gaseous "mini-Neptune". Words and photo: PA.

Instead the planet, known as Kepler-10c, has managed 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 abundant than was thought, and some could be immensely ancient.

The Kepler-10 star system is an estimated 11 billion years old, meaning it formed less than three billion years after the Big Bang that gave birth to the universe.

Earth, by comparison, is only around 4.5 billion years old.

Dr Dimitar Sasselov, from the Harvard Smithsonian Center for Astrophysics, a member of the team that announced the find at the American Astronomical Society's annual meeting in Washington DC, said: "This is the Godzilla of Earths. But unlike the movie monster, Kepler-10c has positive implications for life.

"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."

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.

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.

"Kepler-10c didn't lose its atmosphere over time. It's massive enough to have held onto one if it ever had it - it must have formed the way we see it now."

Commander Chris Hadfield's stunning views from space
See Gallery
New planet discovered: 'Mega earth' is twice as old as Earth and 17 times bigger
"Tonight's Finale: The Richat Structure. A giant gazing eye upon the Earth."
"To commemorate the passing of the Iron Lady, in the centre of these London lights is #10 Downing Street."
"The Australian Outback is effortlessly crazily beautiful."
"The effortless natural art of the southern Sahara."
​"The beautiful and violent ugliness inside a naked volcano. Chad, Africa."
"Beijing just after sunset. I'm still trying to spot the Great Wall, but it's hard as it's narrow and dun-colored."
"A heraldic Spring dragon of ice roars rampant off the coast of Newfoundland."
"Canada rocks."
"Dr. Seuss-inspired swirls in the Black Sea."
"Little farmers, big farmers and nature, in Turkey."
"Big storm swirling off the Irish coast on 9th May."
"A sunny day in Scotland"
"To some this may look like a sunset. But it's a new dawn."
"Hope you Bruins play a memorable game tonight vs the Leafs."

Related stories

In pictures: the world from space

Holiday bucket list: Unusual places to see before you die

New Earth-like planet discovered

Top 9 Surprising Facts About Our Solar System

Read Full Story