Super-Dense Planets May Be Boiled Gas Giant Dregs
The latest addition to the planetary menagerie? Chthonian planets. Super-dense planets, barely larger than Earth, but denser than iron. Now that they’ve been found, astronomers are trying to figure out how they form.
It’s quite likely that these planets, discovered in data acquired by NASA’s Kepler space telescope, are actually the exposed cores of former gas giants. Neptune-sized worlds which have been boiled away, leaving a tightly compressed core to drift naked in space.