Future generations of astronauts could come back wealthy men – Yale scientists have detected a huge ‘super-Earth’ made of diamonds.

The study estimates that at least a third of the planet’s mass - the equivalent of about three times the mass of Earth - could be diamond.

Earth weighs 973600000000000000000000kg, and a kilo of reasonable quality diamonds currently fetches sums of $50 million and above.It orbits a sun-like star 40 light years from Earth, so any mineral prospectors would have quite a journey to stake their claim on its riches. The planet is twice as wide as Earth, and has a mass eight times greater. The planet is thought to be covered in graphite - the material found in the ‘lead’ of pencils - and diamonds."This is our first glimpse of a rocky world with a fundamentally different chemistry from Earth,” said lead researcher Nikku Madhusudhan, a Yale postdoctoral researcher in physics and astronomy."The surface of this planet is likely covered in graphite and diamond rather than water and granite.” The planet – called 55 Cancri e – is one of five planets orbiting a Sun-like star, 55 Cancri, that is located 40 light-years from Earth yet visible to the naked eye in the constellation of Cancer.The planet orbits at hyper speed – its year lasts just 18 hours, in contrast to Earth’s 365 days. It is also blazingly hot, with a temperature of about 3,900 degrees Fahrenheit, researchers said, a far cry from a habitable world.The planet was first observed transiting its star last year, allowing astronomers to measure its radius for the first time. This new information, combined with the most recent estimate of its mass, allowed Madhusudhan and colleagues to infer its chemical composition using models of its interior. The scientists computed all possible combinations of elements and compounds that would yield those specific characteristics.The new research suggests the planet has no water at all, and appears to be composed primarily of carbon (as graphite and diamond), iron, silicon carbide, and, possibly, some silicates.  "By contrast, Earth’s interior is rich in oxygen, but extremely poor in carbon -- less than a part in thousand by mass,” says co-author and Yale geophysicist Kanani Lee."Stars are simple -- given a star’s mass and age, you know its basic structure and history,” said David Spergel, professor of astronomy and chair of astrophysical sciences at Princeton University, who is not a co-author of the study. "Planets are much more complex. This ‘diamond-rich super-Earth’ is likely just one example of the rich sets of discoveries that await us as we begin to explore planets around nearby stars.”In 2011, Madhusudhan led the first discovery of a carbon-rich atmosphere in a distant gas giant planet, opening the possibility of long-theorized carbon-rich rocky planets (or "diamond planets”).  The new research represents the first time that astronomers have identified a likely diamond planet around a Sun-like star and specified its chemical make-up.