[NEWS] Five space science links: ocean worlds, M75, wormholes, neutron stars, black holes, LIGO

• Gizmodo notes the remarkable depth of the oceans of water worlds, going hundreds of kilometres down (or more!).
• Motherboard reports on the latest Hubble images of Messier 75, a star cluster that is the vestige of a galaxy absorbed into the Milky Way.
• Matt Williams at Universe Today notes a new study suggesting that, while traversable wormholes might be physically possible without exotic matter, they would not allow for FTL travel.
• Paul Sutter at Universe Today notes that a closer study of kilonovas might allow for a better understanding of the interior structures of neutron stars.
• Ars Technica notes that LIGO may have detected a collision between a black hole and a neutron star.