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About Saturn & Its Moons

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Rings - Science Objectives

Panoramic Rings
Saturn's dazzling ring system takes center stage here.
Cassini's Equinox Mission science objectives for the rings:

Objectives related to seasonal change:

• Determine production mechanisms of spokes & micro-scale properties of ring structure by observing at seasonally maximum opening angle near Solstice.
• Understand time-variability of ring phenomena on decadal timescales (Encke gap, D ring, ring edges, etc) by substantially increasing time baseline of observations.
• Focus on F ring structure and the distribution of associated moonlets or clumps, as sparse observations show clumps, arcs, and possibly transient objects appearing and disappearing.

Objectives related to new questions raised during Cassini's primary mission:

• Constrain the age of the rings by determining the meteoroid mass infall contamination rate, and by measuring the ring mass.
• Focus on still-unresolved puzzle of how narrow gaps are cleared, by performing deep searches for small embedded moonlets and studying gap edges.
• Determine particle compositional variations at high resolution across selected ring features of greatest interest.
• Conduct in-depth studies of ring microstructure such as self-gravity wakes, which permeate the rings.
• Perform focused studies of the evolution of newly discovered "propeller" objects.

Saturn's Rings at a Glance (Reference: USGS/IAU)

Inner Edge Outer Edge Width
D Ring 66,970 km / 41,632 miles 74,490 km / 46,285 miles 7,500 km / 4,660 miles
C Ring 74,490 km / 46,285 miles 91,980 km / 57,154 miles 17,500 km / 10,874 miles
Colombo Gap 77,800 km / 48,343 miles 100 km / 62 miles
Maxwell Gap 87,500 km / 54,370 270 km / 168 miles
Bond Gap 88,690 km / 55,109 miles 88,720 km / 55,128 miles 30 km / 19 miles
Dawes Gap 90,200 km / 56,048 miles 90,220 km / 56,060 miles 20 km / 12 miles
B Ring 91,980 km / 57,154 miles 117,580 km / 73,061 miles 25,500 km / 15,845 miles
Cassini Division 117,500 km / 73,011 miles 122,050 km / 75,838 4,700 km / 2,920 miles
Huygens Gap 117,680 km / 73,123 miles 285-440 km / 177-273 miles
Herschel Gap 118,183 km / 73,436 miles 118,285 km / 73,499 miles 102 km / 63 miles
Russell Gap 118,597 km / 73,693 miles 118,630 km / 73,713 miles 33 km / 21 miles
Jeffreys Gap 118,931 km / 73,900 miles 118,969 km / 73,924 miles 38 km / 24 miles
Kuiper Gap 119,403 km / 74,194 miles 119,406 km / 74,195 miles 3 km / 2 miles
Leplace Gap 119,848 km / 74,470 miles 120,086 km / 74,618 miles 238 km / 148 miles
Bessel Gap 120,305 km / 74,754 miles 120,246 km / 74,717 miles 10 km / 6 miles
Barnard Gap 120,305 km / 74,754 miles 120,318 km / 74,762 miles 13 km / 8 miles
A Ring 122,050 km / 75,838 miles 136,770 km / 84,985 miles 14,600 km / 9072 miles
Encke Gap 133,570 km / 82,997 miles 325 km / 202 miles
Keeler Gap 136,530 km / 84,836 miles 35 km / 22 miles
Roche Division 136,770 km / 84,836 miles 139,380 km / 86,607 miles 2600 km / 1,616 miles
F Ring 140,224 km / 87,131 miles 30-500 km / 19- 311 miles
G Ring 166,000 km / 103,148 miles 174,000 km / 108119 miles 8,000 km / 4,971 miles
E Ring 180,000 km / 111,847 miles 480,000 km / 298,258 miles 300,000 km / 186,411 miles