Breaking space news, the latest updates on rocket launches, skywatching events and more! You are now subscribed Your newsletter sign-up was successful Want to add more newsletters? An exoplanet so light that it would float on water, were there an ocean large enough, is continuing to frustrate astronomers by concealing its closest secrets with a layer of haze thicker than any ever seen on a planet before. The haze is so thick that not even the vision of the James Webb Space Telescope (JWST) can penetrate it, leaving the mystery of how this ultra-low density world and its sibling planets all formed unsolved for now. "These ultra-low density planets are rare and they defy conventional understanding of how gas giants form," said Jessica Libby-Roberts of the University of Tampa in Florida in a statement. "And if explaining how one formed wasn't difficult enough, this system has three!" Kepler-51d is a member of a four-planet system orbiting a young Sun-like star 2,615 light years away.…