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17

There are four moons that are closer to Jupiter than Io with higher eccentricities, yet they don't seem to have any volcanism at their surface. Only one of those innermost moons (Thebe) has an eccentricity higher than that of Io. The other three have lower eccentricities. The reason they don't exhibit volcanism is because they are too small. The largest of ...


47

It’s because they are much smaller than Io. Tidal forces are differential forces, that is, they result from the difference in gravitational pull on one side of a body compared to the other. When an object is small, the difference in distance to the two sides of it is necessarily small as well. According to Wikipedia, Amalthea, the largest of those four ...


6

tl;dr The inner moons are much to small (and too stiff) to experience significant tidal work. They also cool down much faster though I don't think this is relevant in this case. There're two things to look at, here: The total amount of tidal work that is done on a moon The amount of energy that is radiated away over time When looking at the list of Jupiter'...


7

Jupiter has a sidereal rotation period or day of 9.925 hours. https://en.wikipedia.org/wiki/Jupiter The two innermost moons of Jupiter, Metis and Adrastea, have orbital periods of 7 hours 10 minutes 16 seconds and 7 hours 15 minutes 21 seconds respectively. https://en.wikipedia.org/wiki/Moons_of_Jupiter#List Saturn has a sidereal rotation period or day of 10 ...


12

Uranus rotates once every 0.718 days. 11 of its satellites have a shorter orbital period. These are inner satellites of Uranus which are roughly in the equatorial plane of Uranus. I don't quite understand what direction they orbit in compared to the direction in which Uranus spins. Neptune rotates once every 0.671 days. 5 of its satellites have a shorter ...


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