Yep. A DIAMOND PLANET! Astronomers have discovered a planet twice the size of Earth, made largely out of diamond, which is orbiting a star that is visible with the naked eye. The planet, called '55 Cancri e', orbits a sun-like star 40 light years away in the constellation of Cancer and is moving so fast that a year there lasts a mere 18 hours. Eighteen-hour years! Now that's acceleration!