Astronomy
How Gravitational Interactions Create Gaps in Planetary Rings
Quick fact
Saturn's Cassini Division, a 4,800 km wide gap, is not empty but contains a faint ring. It is kept clear by the gravitational influence of the moon Mimas through a 2:1 orbital resonance.
Why this is interesting
You’ve seen the beautiful rings of Saturn, but did you know they’re riddled with dark gaps? What mysterious force carves these empty lanes through billions of icy particles?