Space Telescope Science
Using Hubble and Spitzer space telescopes, scientists studied the “hot Saturn” called WASP-39b — a hot, bloated, Saturn-mass exoplanet located about 700 light-years from Earth. By dissecting starlight filtering through the planet’s atmosphere into its component colors, the team found clear evidence for a large amount of water vapor. In fact, WASP-39b has three times as much water as Saturn does. Although the researchers predicted they’d see water, they were surprised by how much they found. This suggests that the planet formed farther out from the star, where it was bombarded by a lot of icy material. Because WASP-39b has so much more water than Saturn, it must have formed differently from our famously ringed neighbor.