55 Cancri e: Hellfire Earth

Originally dubbed the “diamond planet,” this steaming hot rocky planet orbits its sun in 14 days. It has a temperature of 4,900 degrees Fahrenheit. Scientists who first discovered it suggested that it was composed entirely of diamonds and graphite. While this interpretation has gone out of favor, it remains an interesting planet because of its density and proximity to its host star. The planet is 40 light years away.

The planet is also thought to have lava flows and at twice the size of Earth. Renyu Hu of the Jet Propulsion Laboratory stated that "If there is lava on this planet, it would need to cover the entire surface… But the lava would be hidden from our view by the thick atmosphere."

While it’s still up to debate, the potentially carbon-rich planet with such high temperatures and pressure could hold a large amount of diamond in its interior.