This first plot shows the orbits of the four moons as seen from above. Rotation around Jupiter (which would be in the center) is counter-clockwise:
The blue line going left points to Earth. The red line going left points to the Sun.
This next plot shows the changes in distance (velocity). The y-axis units are in km/minute and the x-axis is the UT during 11 December 2015:
Line color code:
- Cyan - Io / Europa
- Pink - Io / Ganymede
- Yellow - Io / Callisto
- Green - Europa / Ganymede
- Red - Europa / Callisto
- Blue - Ganymede / Callisto
Also note that at about 16:11 UTC that the pink line and the yellow line cross. This shows that at that moment in time, Io and Ganymede are moving away from each other at exactly the same velocity as Io and Callisto are moving away from each other. HOWEVER, Io is accelerating (positive slope of velocity) towards Ganymede and decelerating (negative slope) towards Callisto!
Very very very coo, and mind blowing and dizzying.
And finally, the mixed sound itself:
The Sound of Velocity