55 Cancri e, discovered in 2004, is a carbon-rich super-Earth about 2 times Earth’s size orbiting a Sun-like star every 18 hours. Its dayside roasts at over 4,000°F (2,200°C), with lava oceans and possible diamond layers from extreme pressure.
This “diamond planet” has a thick atmosphere but no water—too hot for life, just molten rock and gems. JWST has studied it for carbon clues.
It’s one of the closest extreme worlds, showing how planets can be made of stuff wildly different from Earth.