Fear of an Oozing Planet

As writer Ian O'Neill notes here, some of the planets astronomers have been finding in other solar systems are weird.

Among the weird worlds is 55 Cancri e, a planet about 45 light years from Earth orbiting the star 55 Cancri A. It's roughly the size of Neptune and it orbits its star every 18 hours because it's 26 times as close to its star as Mercury is to our sun.

So you'd think it would be a hot ball of half-melted rock, but that's only part of the story. Immense pressures beneath the surface of the planet mean that liquids which would ordinarily boil away remain liquid in a state called "supercritical fluid state." Under great pressure, liquids don't boil at their usual temperatures. Supercritical carbon dioxide, O'Neill notes, is used to decaffeinate coffee beans.

This means that the supercritical fluids ooze to the surface of the planet through cracks in the overheated rocky surface and there sublimate to make an atmosphere we can actually see from 45 light years away. In other words, this thing is a Neptune-sized super-sauna. It is doubtful that any life exists under such extreme conditions, but scientists have theorized that if it did, it would have very open pores.