Jupiter Today | 17 December 2015 | Velocity Audio

Here are the positions of the four Galilean moons of Jupiter over the next 24 hours:

This is a plot showing the relative velocities between the four moons:

Notice that at about 21:00 UTC, all but Io's motion relative to Ganymede is very nearly the same -- in this case, moving toward one another at about 200 km/minute.

Line color code:

• Cyan - Io / Europa
• Pink - Io / Ganymede
• Yellow - Io / Callisto
• Green - Europa / Ganymede
• Red - Europa / Callisto
• Blue - Ganymede / Callisto

And for fun and because these are usually so pretty, the orbital ribbons for today:

And finally, the sound of those velocities:

Velocity Audio | Jupiter Today 17 December 2015