APOD: 2026 October 28: The Mutual Occultation of Ganymede and Io

A video shows Ganymede briefly blocking Io from view on Oct. 20, 2026, a mutual occultation of two of Jupiter's Galilean moons. These events are rare because they need an edge on view of the moons' orbits, which happens about once every six years when Jupiter reaches its equinox. Ganymede also cast its shadow on Jupiter's right side, so this is a chance that does not come around often.