While astronomers nowadays are able to look across distant space, and learn something about the sizes and orbits of the super-Earths, they’d like to know … what are super-Earths made of? Or a super-Earth might be a water world … a rocky core enveloped in a blanket of water and perhaps an atmosphere composed of steam (depending on the temperature of the planet). Information about the atmosphere could help astronomers determine which one it was: a mini-Neptune’s atmosphere should contain lots of molecular hydrogen, while a water world’s atmosphere should be water dominated.