4 Billion Years Ago a Giant Impact Reshaped Jupiter's Largest Moon  ScienceAlertJupiter’s moon Ganymede was struck by asteroid bigger than dinosaur-killing rock  The GuardianHuge asteroid impact may have knocked over Jupiter's largest moon  New ScientistAncient impact shattered Ganymede and knocked it off its axis  New AtlasGiant impact on early Ganymede and its subsequent reorientation - Scientific Reports  Nature.com