Some exoplanets—like a gas giant with rain made of glass and 5,000-mile-per-hour winds—sound like worlds dreamed up by a science fiction writer. But they’re real. From light-years away, scientists can uncover details about planets orbiting distant stars and even ask whether some exoplanets could support life. Néstor Espinoza, an astronomer at the Space Telescope Science Institute, explains how NASA’s James Webb Space Telescope is revealing new details about exoplanets, especially rocky worlds like Earth.