Uranus’s 97.77-degree axial tilt has been hypothesized as the result of a single large impact that knocked the ice giant on its side. But a team of researchers argue if that were the case, Uranus’s moons would be left orbiting in their original position, instead of matching Uranus’s weird tilt. They suggest, based on computer modelling, that Uranus was smacked while still in possession of its protoplanetary disk (i.e., before its moons formed) and that it was smacked more than once (because a single hit would have had the moons orbiting in the opposite direction). Which means that large impacts may not have been rare in the early solar system. Via io9 and Universe Today. Image credit: Lawrence Sromovsky, (Univ. Wisconsin-Madison), Keck Observatory.