Has Project Hail Mary left you craving more of Andy Weir's work? We've rounded up the best of Andy Weir's sci-fi books, from The Martian to Artemis.
There are some strange types of exoplanets out there with no counterparts in our Solar System. One of those types is super-puff planets. These oddballs have radii larger than Neptune, but only have a few Earth masses. This means they have large volumes and low density. How this peculiar type of exoplanet forms is unclear, and current models of gas giant formation can't account for them.

