Hi Dave,

I think that you are talking about the observations made by the Cassini spacecraft of geyser's on Saturn's moon Enceladus. Enceladus is not in a perfectly circular orbit around Saturn, so the gravitational pull Enceladus feels from Saturn changes over the course of its orbit. As Enceladus is stretched and squeezed by the resulting tidal forces, the gravitational energy is transformed into heat energy far below the moon's surface. The heat energy produced by the tidal forces drives the geologic activity (the geysers) Cassini observed on Enceladus.

I can't think of any way that the Sun may contribute to this type of geologic activity, since Saturn is very far away from the Sun and the geysers on Enceladus are thought to be driven by tidal forces. However, a special alignment of Enceladus with the Sun helped make the geysers visible. Scientists were able to see the plumes of water vapor erupting from the geysers on the surface of Enceladus because the Sun was just behind Enceladus and illuminated the rising plume of water vapor.

Kris