Astronomers discover 'diamond planet' twice the size of Earth

Researchers say at least a third of the planet could consist of diamond Credit: REUTERS/Luke MacGregor

Astronomers believe they have discovered a planet that is twice the size of Earth and encrusted with diamonds.

The planet, called '55 Cancri e', is orbiting around a sun-like star that is visible to the naked eye. It is moving in its orbit so fast that a year there lasts a mere 18 hours.

A team of American and French researchers believe the planet has a mass eight times greater than our own and is therefore much denser.

It is also incredibly hot, with a surface temperatures of 1,648°C.

One of the researchers, Dr Nikku Madhusudhan from Yale University in the US, said:

Their research, due to appear in the Astrophysical Journal Letters, suggests that at least a third of the planet could consist of diamond.

Our solar system (top) compared with a the planetary system 55 Cancri Credit: REUTERS/Stringer

Astronomers discovered the planet last year when they studied an incredibly subtle dimming of light as 55 Cancri e passed in front of its sun.

After calculating the planet's size and mass, scientists were able to make inferences about its chemical make-up.

Dr Madhusudhan said the discovery shows scientists that distant rocky planets can no longer be assumed to have chemical constituents, interiors, atmospheres or biologies similar to Earth.

Professor David Spergel, from Princeton University in the US, said:

Read more about 55 Cancri e on the NASA website.