Hi All

According to an analysis by J. Wisdom, Enceladus is in a special resonance so it is experiencing enhanced energy dissipation - thus the very bright, very recent resurfacing of that little moon. It's only 500 km across, yet it may have sub-surface "oceans" because of the period-three librational resonance. Europa is undergoing a forced libration that is in a 3:1 resonance with its orbit and this leads to a 100-1000 fold tidal heating rate.

One thing I noticed is a model of Enceladus he works off has a low density (~ 1.0), but according to NASA it's closer to 2. I'm wondering if that enhances the libration's magnitude even further.

Adam