A nice day at Jupiter today.
Notice that at about 05:08 UTC, the distances between Ganymede / Callisto, Europa / Ganymede, and Io / Callisto are all about the same. Pretty nice! Notice also that this three-distance convergence involves all four moons.
Here are the orbits:
and here are the distances:
Here is the sound of the distances:
Jupiter Today 09 December 2015