Explanation: Jupiter is one of the least lonely planets in the Solar System, at least when it comes to
natural satellites.
115 moons have been discovered orbiting Jupiter so far! (
Saturn has the most with 293, but who’s counting.)
Ganymede and
Io, two of Jupiter’s
Galilean moons, met in the sky on October 20th, 2026. Today’s video captures the meeting, with
Ganymede briefly blocking
Io from view. This event, when an astronomical object passes in front of another and either completely or partially blocks it, is called a mutual occultation. The
mutual occultations of Galilean moons are rare to witness because they require Earth’s edge-on view of their orbits. This occurs once every 6 years when Jupiter reaches
its equinox and appears less “tilted”. Ganymede is also
casting its shadow on Jupiter’s right side. Any
fictional Jovian species within the shadow would experience a
solar eclipse!
Tomorrow's picture: a planet grows horns