The third-largest object known beyond Neptune, 2007 OR10, has a moon. The discovery was reported in a poster by Gábor Marton, Csaba Kiss, and Thomas Mueller at the joint meeting of the European Planetary Science Congress and the Division for Planetary Sciences of the American Astronomical Society (DPS/EPSC) on Monday.
What is the solar system moon with the densest atmosphere? Most space fans know that the answer is Titan. A few of you might know that Triton's is the next densest. But what's the third? Fourth? Do any other moons even have atmospheres? In fact, they do; and one such atmosphere has just been discovered.
A newly published paper confirms a subsurface ocean at Ganymede. An ocean there was already suspected from its magnetic field and predicted by geophysics; new Hubble data confirms it, and even says it is in the same place we thought it was before. Such consistency is rare enough in planetary science to be worth celebration.