MrSeb writes: "Scientists at Yale University have discovered a nearby super-Earth that is a “diamond planet” — a planet that has a mantle made of graphite and diamond. The planet, called 55 Cancri e, is just 40 light years from Earth and orbits the binary star 55 Cancri, which is located in the constellation of Cancer. When the planet was first observed last year, it was originally thought to be a water planet, similar to Earth, but new information has allowed the scientists to infer that the planet is much more likely to be a diamond planet. The Yale scientists estimate that as much as one third of 55 Cancri e’s mass is made up of diamond — the same as three Earth masses, or roughly 18×1024kg. This is a few trillion times more diamond than has ever been mined on Earth. The identification of just a single diamond-rich planet is massive news. In recent years we have identified hundreds of rocky, Earth-like planets — and until now, we had assumed they had similar make-ups. It is now fairly safe to assume that there are millions of diamond planets in the universe."