Vital Statistics for Saturn’s Rings

Rings of Saturn

Feature Inner Boundary (km) Outer Boundary (km) Optical Depth Type Associated Moons Footnotes Comments
D Ring 66,900 74,491 10-5 to 10-3 Tenuous, Broad   1,10 Contains narrow ringlets at 67,580 and 71,710 km.
C Ring 74,491 91,975 0.05 to 0.35 Dense, Broad   1,10 Contains isolated “plateaus” among a surrounding, fainter ring.
Colombo Gap 77,748 77,926 ~0 Gap   7  
Titan Ringlet 77,867 77,890 ~4 Dense, Narrow Titan 7 Ringlet that occupies outer third of Colombo Gap. Also known as Colombo Ringlet.
Maxwell Gap 87,343 87,610 ~0 Gap   7 Widest gap in the C Ring.
Maxwell Ringlet 87,480 87,539 1 to 3 Dense, Narrow   7 A narrow, eccentric ringlet inside a gap in the C Ring.
Bond Gap 88,686 88,723 ~0 Gap   7 Gap due to second-order resonance with Mimas.
Bond Ringlet 88,702 88,719 ~1 Dense, Narrow   7 A narrow, sharp-edged ringlet inside a gap in the C Ring.
Dawes Gap 90,200 90,221 ~0 Gap   7 Very narrow gap
Dawes Ringlet 90,138 90,200 0.2 to 1 Dense, Narrow   7 This feature has been referred to as ringlet, but it is not detached from the rest of the C ring.
B Ring 91,975 117,570 0.4 to 5 Dense, Broad   1,11 Contains fine structure on all scales. The most opaque of Saturn’s rings.
Region B1 91,975 99,000 1.1 to 1.5 Dense, Broad   9 Innermost region of B Ring. Characterized by undulations in optical depth and I/F.
Region B2 99,000 104,000 1.5 and >4 Dense   9 Central region of B Ring. Characterized by alternating zones of high and low optical depth.
Region B3 104,000 110,000 1 to 5 Dense   9 Central region of B Ring. Characterized by high optical depth. Median optical depth is 3.6, the highest of any region in the rings.
Region B4 110,000 116,500 2 to 3 Dense   9 Outer region of B Ring. Here the optical depth gradually decreases, but in an irregular way.
Region B5 116,500 117,500 0.5 to >5 Dense Mimas 9 Outermost region of B Ring, affected by its highly variable outer edge.
Cassini Division 117,500 122,050 0 to 0.2 Dense, Broad   10,11 The prominent gap between the A and B Rings. It contains several features of low optical depth.
Huygens Gap 117,500 117,930 ~0 Gap Mimas 8  
Huygens Ringlet 117,806 117,824 1 to 2 Dense, Narrow   8  
Strange Ringlet 117,907 117,909   Dense, Narrow   8  
Herschel Gap 118,188 118,284 ~0 Gap   8 Approximate boundaries based on Table 3 of Ref 8.
Herschel Ringlet 118,234 118,263 ~0.1 Dense, Narrow   8 A narrow, eccentric, inclined ringlet near the inner edge of the Cassini Division.
Russell Gap 118,590 118,628 ~0 Gap   8  
Jeffreys Gap 118,930 118,967 ~0 Gap   8  
Kuiper Gap 119,402 119,406 ~0 Gap   8  
Laplace Gap 119,845 120,086 ~0 Gap   8  
Laplace Ringlet 120,037 120,078 ~1 Dense, Narrow   8  
Bessel Gap 120,231 120,244 ~0 Gap   8  
Barnard Gap 120,304 120,316 ~0 Gap   8  
A Ring 122,050 136,770 0.4 to 1 Dense, Broad   10,12 A fairly uniform ring with many density and bending waves, especially near its outer edge.
Encke Gap 133,423 133,745 ~0 Gap Pan 10 A gap in the A Ring maintained by the embedded moon Pan. One or more faint ringlets are also present.
Keeler Gap 136,487 136,522 ~0 Gap Daphnis 10 A narrow gap in the outer A Ring maintained by the embedded moon Daphnis.
Roche Division 136,770 139,380 ~10-4 Tenuous, Broad Atlas, Prometheus 6 The separation between outer edge of A Ring and the F Ring.
F Ring 139,826 140,612 0.01 to 0.2 Narrow Prometheus, Pandora 1,13 A complex, narrow, eccentric, inclined ring with a denser core at a=140,224 km demonstrating a wide variety of quasi-stable and ephemeral structure.
Janus/Epimetheus Ring 149,000 154,000 10-7 Tenuous Janus, Epimetheus 2 A narrow, very faint ring in the region occuppied by Janus and Epimetheus.
G Ring 166,000 173,200 10-6 Tenuous Aegaeon 1 A faint, isolated dust ring.
E Ring 180,000 480,000 5x10-6 Tenuous Enceladus 1 A broad, faint dust ring encompassing the orbits of Mimas through Dione. Densest near the orbit of Enceladus. Up to ~30,000 km in vertical extent.
Methone Ring ~194,440   ~10-7 Tenuous Methone 3 A narrow, very faint ring in the the region occuppied by Methone.
Anthe Ring ~197,655   ~10-7 Tenuous Anthe 4 A narrow, very faint ring in the orbit of Anthe.
Pallene Ring ~212,280   ~10-7 Tenuous Pallene 2 A narrow, very faint ring in the region occuppied by Pallene.
Phoebe Ring 7,720,000 12,500,000 ~2x10-8 Tenuous Phoebe 5 A broad, faint ring in the orbit of Phoebe with a vertical extent of ~2,400,000 km.

The table of Saturn’s regular satellites can be found here.

Sources

  1. Murray, C.D., and S.F. Dermott 1999. Solar System Dynamics, Cambridge University Press. DOI:10.1017/CBO9781139174817

  2. Porco, C.C., and the Cassini Imaging Team 2006. Rings of Saturn (R/2006 S 1, R/2006 S 2, R/2006 S 3, R/2006 S 4). IAU Circulars 8759

  3. Roussos, E., et al. 2008. Energetic electron signatures of Saturn’s smaller moons: Evidence of an arc of material at Methone. Icarus 193, 455-464. DOI:10.1016/j.icarus.2007.03.034

  4. Porco, C.C., on behalf of the Cassini Imaging Team, 2008. R/2006 S 5 and R/2007 S 1. IAU Circulars 8970.

  5. Verbiscer, A.J., Skrutskie, M.F., and D.P. Hamilton 2009. Saturn’s largest ring, Nature 461, 1098-1100. DOI:10.1038/nature08515

  6. The Gazetteer of Planetary Nomenclature, https://planetarynames.wr.usgs.gov/Page/Rings

  7. Nicholson, P.D., et al. 2014. Noncircular features in Saturn’s rings II. The C ring. Icarus 241, 373-396. DOI:10.1016/j.icarus.2014.06.024

  8. French, R.G., et al. 2016. Noncircular features in Saturn’s rings III. The Cassini Division. Icarus 274, 131-162. DOI:10.1016/j.icarus.2016.03.017

  9. Colwell, J.E., et al. 2009. The structure of Saturn’s rings, In M.K. Dougherty et al. (eds), Saturn from Cassini-Huygens, Springer, London, 375-408. DOI:10.1007/978-1-4020-9217-6

  10. French, R.G., et al. 2017. Noncircular features in Saturn’s rings IV. Absolute radius scale and Saturn’s pole direction. Icarus 290, 14-45. DOI:10.1016/j.icarus.2017.02.007

  11. Nicholson, P.D., et al. 2014. Noncircular features in Saturn’s rings I. The edge of the B ring. Icarus 227, 152-175. DOI:10.1016/j.icarus.2013.09.002

  12. El Moutamid, M., et al. 2016. How Janus’ orbital swap affects the edge of Saturn’s A ring. Icarus 279, 125-140. DOI:10.1016/j.icarus.2015.10.025

  13. Cooper, N.J., Murray, C.D., Williams, G.A. 2013. Local variability in the orbit of Saturn’s F ring. The Astronomical Journal 145, 161. DOI:10.1088/0004-6256/145/6/161

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