Researchers at Yale have found the first evidence of a new diamond planet, a type of planet that usually only exists in theory and fiction. The planet, called 55 Cancri e, was discovered last year and initially assumed to have a similar chemical makeup to Earth. However, researchers were able to infer the planet's composition from recent mass and radius measurements, by "computing all possible combinations of elements and compounds" that would match those measurements. Using this technique, the researchers discovered that 55 Cancri e consists primarily of carbon in the form of graphite and diamond, as well as iron, silicon carbide, and some silicates.
55 Cancri e is different from Earth in many ways, not least because over one third of the planet could be diamond. The planet — which orbits a sun in the constellation of Cancer — has a radius twice that of Earth, a mass about eight times greater, and revolves around its sun in just 18 hours. The surface of the planet is estimated at about 3,900 degrees Fahrenheit, and the extreme heat combined with pressure over time likely caused the carbon of the planet to turn to diamond. "This is our first glimpse of a rocky world with a fundamentally different chemistry from Earth," remarked lead researcher Nikku Madhusudhan, and this finding could lead to a new way of looking at yet undiscovered planets.