An exoplanet in a star’s Goldilocks zone is confirmed to have water

SINCE ITSK2-K2-K2- discovery by astronomers in 2015, the exoplanet 18b has elicited much excitement. Swirling around a red-dwarf star about 110 light-years away from Earth, the distant world sits in a so-called Goldilocks zone—not close enough to its host star to be too hot and not far enough away to be too cold—that could allow liquid water to flow across its surface. And liquid water is a crucial condition for any sort of remotely Earthlike life.Now astronomers have cranked up the speculation. Follow-up images taken by the Hubble Space Telescope suggest 18b (artist’s impression below) has an atmosphere containing large amounts of water vapour—the first exoplanet in a habitable zone to have this confirmed. Most exoplanets previously found with atmospheres have been gas giants, similar to Neptune or Jupiter. 18b instead looks like it could be a rocky planet with between two and three times the diameter of Earth, perhaps covered in vast ice-covered seas.