Astronomy Picture of the Day

Explanation: Why does Saturn's moon Pan look so odd? Images taken last week from the robotic Cassini spacecraft orbiting Saturn have resolved the moon in unprecedented detail. The surprising images reveal a moon that looks something like a walnut with a slab through its middle. Other visible features on Pan include rolling terrain, long ridges, and a few craters. Spanning 30-kilometre across, Pan orbits inside the 300-kilometre wide Encke Gap of Saturn's expansive A-ring, a gap known since the late 1800s. Next month, Cassini will be directed to pass near Saturn's massive moon Titan so it can be pulled into a final series of orbits that will take it, on occasion, completely inside Saturn's rings and prepare it to dive into Saturn's atmosphere.