If you could somehow place WASP-193b in a cosmic bathtub, it would float.. and not just barely. This exoplanet, located 1,200 light-years away, has a density of just 0.059 grams per cubic centimeter. That's roughly the same as cotton candy.

For perspective: Earth has a density of 5.5 g/cm³, Jupiter is 1.3 g/cm³, and even the least dense planet in our solar system, Saturn, comes in at 0.69 g/cm³. WASP-193b is an order of magnitude lighter than anything we've seen. The planet is 50% larger than Jupiter but weighs only about 14% as much—making it the second-lightest planet ever discovered, according to the research published in Nature Astronomy.

"The planet is so light that it's difficult to think of an analogous, solid-state material," said MIT professor Julien de Wit. "The reason why it's close to cotton candy is because both are mostly made of light gases rather than solids. The planet is basically super fluffy." What baffles scientists is that a planet this massive should have collected far more hydrogen and helium during formation. Current planetary models cannot explain how WASP-193b inflated so dramatically while maintaining such an impossibly low density. It took researchers four years just to confirm the planet's mass because it barely tugged on its star at all.