The Sound of Velocity | Jupiter Today 11 December 2015

So instead of listening to the distances between the four Galilean moons of Jupiter, today I'm listening to the changes in distance -- otherwise known as velocity.

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

So in the plot above, the pink line shows the velocity between Io and Ganymede.  At 0h UTC, these two moons are moving away from one another at a velocity of about 800 km/minute.  By about 13:30 UTC, the relative velocities between the two moons is zero km/minute.  By the end of the day, the two moons are moving away from another at a velocity of almost 800 km/minute.

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