Candy-Floss Planets: Why Some Worlds Weigh Less Than They Have Any Right To

Imagine a planet the size of Jupiter but lighter than a feather duster—these "super-puffs" have atmospheres so puffed up that the planet itself is mostly empty space.

This means our models of how planets form and evolve are still missing crucial pieces, and these featherweight worlds are forcing us to rethink what's possible in planetary systems.