The rocky planet, called ‘55 Cancri e’, orbits a sun-like star in the constellation of Cancer and is moving so fast that a year there lasts a mere 18 hours. Discovered by a US-Franco research team, its radius is twice that of Earth’s but it is much more dense with a mass eight times greater. It is also incredibly hot.
“The surface of this planet is likely covered in graphite and diamond rather than water and granite,” said Nikku Madhusudhan, the Yale researcher whose findings are due to be published.
The study estimates that at least a third of the planet’s mass, the equivalent of about three Earth masses, could be diamond. Diamond planets have been spotted before but this is the first time one has been seen orbiting a sun-like star and studied in such detail.
“This is our first glimpse of a rocky world with a fundamentally different chemistry from Earth,” Madhusudhan said.