View Full Version : How much tidal heating does Amalthea have?

Tom Mazanec
2004-May-29, 04:06 PM
Amalthea is a good bit closer to Jupiter than Io, and Io should be perturbing its orbit, so it should have much more tidal heating per size than Io (it's a square of a cube, right?). Of course, it is way smaller, but I wonder if it is still noticably warmed?

Brady Yoon
2004-May-29, 04:10 PM
I'm not exactly sure... good question. If Amalthea was the same size as Io, the tidal effects would be the same, but since Amalthea is much smaller, the tides would be smaller. I'm not sure which factor is more important. :-k

2004-May-29, 08:16 PM
Amalthea, being very small, has a large surface area to volume ratio. That means that it can dissipate heat very quickly, and it probably wouldn't be able to build up enough heat to melt its interior.

Also, Amalthea has no significant gravity to hold itself together. Strong tides would rip it apart.

Tom Mazanec
2004-May-30, 04:11 PM
Well, Amalthea is not in the Roche lobe, so it would not disrupt even if it were a gravel pile. But it is less than half Io's distance, so its tidal bulge would be ten or twelve times bigger than Io's if it were the same size (it would make Io look like a snowball). It's small size makes it inactive, but I would still expect it to be warmed a little.

Kullat Nunu
2004-May-30, 06:14 PM
When Galileo passed Amalthea the moon's density was found to be very low. Yet it is believed to be composed of rocks instead of water ice, so it probably really is a gravel pile.

2004-May-31, 01:47 AM
Also, if understand correctly. The tides on Io are caused by its orbital resonance with Europa. Tugged on in two directions by Jupiters and Europas gravitational influence. I don't think Amalthea is in a resonance orbit.

2004-May-31, 02:48 AM
The tides on Io are caused by its orbital resonance with Europa.

Yep, and Ganymede, and if I'm not mistaken, partially(?) Callisto.