열람 Cassini Division
The Cassini Division is a 4,800 km (2,980 mile) wide region between the A Ring and B Ring. It was discovered in 1675 by Giovanni Cassini. From Earth it appears as a thin black gap in the rings. However, Voyager discovered that the gap is itself populated by ring material bearing much similarity to the C Ring.[24] The division may appear bright in views of the unlit side of the rings, since the relatively low density of material allows more light to be transmitted through the thickness of the rings (see second image in gallery).[citation needed]
The inner edge of the Cassini Division is governed by a strong orbital resonance. Ring particles at this location orbit twice for every orbit of the moon Mimas.[citation needed] The resonance causes Mimas’ pulls on these ring particles to accumulate, destabilizing their orbits and leading to a sharp cutoff in ring density. Many of the other gaps between ringlets within the Cassini Division, however, are unexplained.[citation needed]
[edit]Huygens Gap
The Huygens Gap is located at the inner edge of the Cassini Division. It contains a dense eccentric ringlet named Huygens Ringlet in the middle. This ringlet demonstrates irregular azimuthal variations of the geometrical width and optical depth, which can be caused by the nearby strong 2:1 resonance with Mimas and by the influence of the eccentric outer edge of the B-ring. There is an additional narrow ringlet just outside the Huygens Ringlet.[24]