A rare exoplanet that should have been stripped down to bare rock by its nearby host star’s intense radiation somehow grew a puffy atmosphere instead—the latest in a string of discoveries forcing scientists to rethink theories about how planets age and die in extreme environments.

The findings could help scientists better understand how atmospheres like Earth’s might evolve. Scientists predict that in a few billion years the sun will expand into a red giant star that will swell up and engulf Earth and the other inner planets.

We don’t understand the late-stage evolution of planetary systems very well, this is telling us that maybe Earth’s atmosphere won’t evolve exactly how we thought it would

Puffy planets are often composed of gases, ice, or other lighter materials that make them overall less dense than any planet in the solar system. They are so rare that scientists believe only about 1% of stars have them.