Two tiny moons of Saturn, almost lost amid the planet’s enormous rings, are seen orbiting in this Cassini probe image. Pan, visible within the Encke Gap near lower-right, is in the process of overtaking the slower Atlas, visible at upper-left.
Voyager 2 made its closest approach to Saturn 35 years ago — on 25 August 1981. What the Voyagers revealed at the planet was so phenomenal that, just one year later, a joint American and European working group began discussing a mission that would carry on Voyager’s legacy at Saturn.
In this image from NASA’s Cassini spacecraft, Saturn’s moon Dione reveals its past via contrasts. The features visible here are a mixture of tectonics — the bright, linear features — and impact cratering — the round features, which are spread across the entire surface.
Pan and moons like it have profound effects on Saturn’s rings. The effects can range from clearing gaps, to creating new ringlets, to raising vertical waves that rise above and below the ring plane. All of these effects, produced by gravity, are seen in this image from the Cassini probe.