Cassini Rings Science

PIA22418 is the highest-resolution color images of any part of Saturn's rings, to date, showing a portion of the inner-central part of the planet's B Ring.

On this page:

  • Overview: Important information for any type of study of Saturn's Rings
  • Finding Data: Find, browse, and download data
  • Analyzing Data: Software tools and publications related to the analysis of data on Saturn's Rings

Ring-Moon Systems Node on PDS >


The purpose of this page is to provide an understandable, consistent, and accessible home for Cassini Rings Science Discipline data. This page also contains an overview of Saturn's Rings and a guide to software analysis tools. However, the bulk of the rings data is really stored, with additional tools and contact information, on the PDS Rings-Moon Node.
The Saturn's Rings Sections in Cassini Mission Final Report (in preparation) summarizes the status of Saturn's rings, in 2018, as a result of Cassini exploration of the Saturn system. It also includes open questions that will be explored by future scientists.

Charm Talks is a series of talks given by the team that provides insight into discovery and development of understanding

Mission Objectives

  • Study configuration of rings and dynamic processes (gravitational, viscous, erosional and electromagnetic) responsible for ring structure.
  • Map composition and size distribution of ring material.
  • Investigate interrelation of rings and satellites, including embedded satellites.
  • Determine dust and meteoroid distribution in ring vicinity.
  • Study interactions between rings and Saturn's magnetosphere, ionosphere and atmosphere.

Ring Property Summary Table

Name Inner Boundary Outer Boundary Optical Depth Type Associated Satellites Comments
D Ring 66900 km 74491 km 0.00001 to 0.001 Tenuous, Broad Contains narrow ringlets at 67580 and 71710 km
C Ring 74491 km 91975 km 0.05 to 0.35 Dense, Broad Isolated "plateaus" among a surrounding, fainter ring; contains ≥ 8 narrow gaps
Titan Ringlet 77867 km 77890 km ~4 Dense, Narrow A narrow, eccentric ringlet inside a gap in the C ring
Maxwell Ringlet 87480 km 87539 km 1 to 3 Dense, Narrow A narrow, eccentric ringlet inside a gap in the C ring
Bond Ringlet 88702 km 88719 km ~1 Dense, Narrow A narrow ringlet inside a gap in the C ring
Dawes Ringlet 90138 km 90200 km 0.2 to 1 Dense, Narrow A narrow, eccentric feature interior a gap in the C ring
B Ring 91975 km 117570 0.8 to 5 Dense, Broad Contains fine structure on all scales. The most opaque and massive of Saturn's rings
Cassini Division 117570 km 122050 km 0 to 0.2 Dense, Broad The prominent gap between the A and B Rings. It contains 8 narrow gaps and > 4 ringlets
Huygens Ringlet 117806 km 117824 km 1 to 2 Dense, Narrow A narrow, eccentric ringlet near the inner edge of the Cassini Division
Herschel Ringlet 118234 km 118263 km ~0.1 Dense, Narrow A narrow, eccentric, inclined ringlet near the inner edge of the Cassini Division
Laplace Ringlet 120037 km 120078 km ~1 Dense, Narrow A narrow, eccentric ringlet in the Cassini Division
A Ring 122050 km 136780 km 0.4 to 1.0 Dense, Broad A fairly uniform ring with many density and bending waves near its outer edge
Encke Gap 133423 km 133745 km Gap Pan A gap in the A Ring maintained by the embedded moon Pan. Multiple faint ringlets are also present.
Keeler Gap 136487 km 136522 km Gap Daphnis A narrow gap in the outer A Ring maintained by the embedded moon Daphnis.
Roche Division 136780 km 139800 km ~0.0001 Tenuous, Broad Atlas, Prometheus A dust sheet extending between the A and F Rings
F Ring 139800 km 140600 km 0.01 to 0.2 Narrow Prometheus, Pandora A complex, narrow, eccentric, inclined ring with a dense core at a=140223.92 km demonstrating a wide variety of quasi-stable and ephemeral structure.
Janus/Epimetheus Ring 149000 km 154000 km ~10-7 Tenuous, Narrow Janus, Epimetheus A narrow, very faint ring in the region occupied by Janus and Epimetheus
G Ring 166000 km 173200 km ~10-6 Tenuous, Narrow Aegaeon A faint, isolated dust ring, contains an arc of material confined by a narrow resonance with Mimas
E Ring 180000 km 480000 km ~5x10-6 Tenuous, Broad Enceladus A broad, faint dust ring encompassing the orbits of Mimas through Dione. Densest near the orbit of Enceladus. Up to ~30000 km thick.
Methone Ring ~194400 km ~10-7 Tenuous, Narrow Methone A narrow, very faint ring in the region occupied by Methone.
Anthe Ring ~197655 km ~10-7 Tenuous, Narrow Anthe A narrow, very faint ring in the region occupied by Anthe.
Pallene Ring ~212000 km ~10-7 Tenuous, Narrow Pallene A narrow, very faint ring in the region occupied by Pallene.
Phoebe Ring 7722200 km 12488300 km ~2x10-8 Tenuous, Broad Phoebe A broad, faint ring in the orbit of Phoebe with a vertical extent of 2,413,200 km.
PIA08389 shows a mosaic of a radial scan across Saturn's main rings.

Key Publications

  • In Planetary Ring Systems. (M.S. Tiscareno and C.D. Murray, Eds). Cambridge (2018)
  • In Saturn from Cassini-Huygens (M.Dougherty, L. W. Esposito, and S. M. Krimigis, Eds). Springer (2009)
  • Rings Final Report - this document attempts to cover the highlights of ring science from beginning to end of the mission as organized by the ring scientists' goals and objectives, and to provide a thread of continuity connecting Cassini's vast accomplishments to the big picture of ring origin and evolution.

Finding Ring Data


These instruments were used to study Saturn's ring system.
  • CIRS - Composite Infrared Spectrometer
    Infrared studies of temperature and composition of surfaces
  • ISS - Imaging Science Subsystem
    Multispectral visible-light imaging of icy satellites to observe their properties
  • UVIS - Ultraviolet Imaging Spectrograph
    Ultraviolet spectra and low-resolution imaging for chemistry and composition
  • VIMS - Visual and Infrared Mapping Spectrometer
    Visible and infrared spectral mapping to study composition and structure of surfaces
  • RADAR - Radio Detection and Ranging
    SAR mapping, scatterometry, altimetry data using active RADAR, radiometry data to measure ring temperature
  • RSS - Radio Science Subsystem
    Study of atmospheric and ring structure, gravity fields and gravitational waves

Data Search Tools

Searching by Parameters:

  • OPUS is a search tool at the Ring-Moon Systems Node for CIRS, ISS, UVIS and VIMS data with a wide variety of search parameters including the target body, distance, and illumination conditions. It has both surface and ring geometry search parameters so is equally useful for ring and surface/atmosphere science goals
  • The PDS Image Atlas is a search tool at the Cartography and Imaging Sciences Node for ISS, RADAR and VIMS data with a wide variety of search parameters including the target body, distance, and illumination conditions. However it is designed to locate surface data i.e. observations of planetary and satellite surfaces/atmospheres and only the ISS data has any ring target search parameters. OPUS is a significantly more powerful tool for locating ring data.
  • CIRS Rings Observation Database (In preparation at the Rings-Moon Node)

Searching by Mission Events:

  • The Event Calendar helps search for observations of rings and related events such as ring-plane crossings.

Jovian Ring Observations:

  • Jovian Ring Observations (csv) during the Cassini Jupiter flyby spanned the interval from September 26, 2000 to January 15, 2001.
  • Targeted Jupiter data was near closest approach.

Browsing raw data:

Derived Data

Supplemental Reference Documents

  • Ring Models used by Cassini: Document written by Jeff Boyer, the Cassini Project's Pointing Design software guru, describing the models used to represent the saturnian rings for planning purposes as well as details of the individual modules used in the observation planning software for designing rings observations.
  • Ring Observation Key: Fairly detailed summaries of the general characteristics of various types of Rings observations. Most, but not necessarily all, ring observations with at least ten instances are included. Not all ring observation types are described and "one off" unique observations are not covered.
  • Observation Notes for VIMS Activities: A few brief notes made by Phil Nicholson for some of the VIMS observations he was personally responsible for.
  • CIRS Rings Target Notebook
  • Planning products: These can provide some context for observations from the science planning point of view. These are the work product of the relevant Target Working Team (TWT) at the end of the process that allocates time and data volume to individual science observations.
    Time-Ordered Listings (TOLs) , Graphical Timelines and Sequence Handoff Packages
    Cross-Discipline (XD)

Analyzing Ring Data

Software Tools

SPICE examples

Examples showing segments of SPICE code (in multiple languages - FORTRAN, IDL and maybe C) that perform rings type calculations.
  • How to find the Ring/Equator plane intercept

For questions and comments, visit the PDS Cassini Contact Page