55 Cancri e is an extrasolar planet approximately 40 light years from Earth orbiting the Sun-like star 55 Cancri A. Its mass is about 7.8 Earth masses and its diameter is about twice that of Earth's, thus classifying it as the first Super-Earth discovered around a main sequence star. 55 Cancri E is believed to be a solid planet made of carbon-rich material rather than the oxygen-rich material that makes up the terrestrial planets in our solar system. As such, roughly a third of the planet's mass would be carbon. Due to conditions in the planet’s atmosphere, much of this mass may be diamond.