A Short History of Astronomy ()/Chapter 13 - Wikisource, the free online library
Phoebe orbits the planet at a distance ranging from to radii. The ring has a thickness of about 40 radii. This ring lies in the plane of Saturn's orbit, or roughly the ecliptic , and thus is tilted 27 degrees from Saturn's equatorial plane and the other rings. The existence of the ring was proposed in the s by Steven Soter.
Verbiscer and Michael F. Skrutskie of the University of Virginia and Douglas P. Hamilton of the University of Maryland, College Park. Infall of this material causes a slight darkening and reddening of the leading hemisphere of Iapetus similar to what is seen on the Uranian moons Oberon and Titania but does not directly create the dramatic two-tone coloration of that moon.
This leaves a dark residue of "lag" material covering most of the equatorial region of Iapetus's leading hemisphere, which contrasts with the bright ice deposits covering the polar regions and most of the trailing hemisphere. Saturn's second largest moon Rhea has been hypothesized to have a tenuous ring system of its own consisting of three narrow bands embedded in a disk of solid particles.
The Magnetospheric Imaging Instrument MIMI observed a gentle gradient punctuated by three sharp drops in plasma flow on each side of the moon in a nearly symmetric pattern.
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This could be explained if they were absorbed by solid material in the form of an equatorial disk containing denser rings or arcs, with particles perhaps several dm to approximately a m in diameter. A more recent piece of evidence consistent with the presence of Rhean rings is a set of small ultraviolet-bright spots distributed in a line that extends three quarters of the way around the moon's circumference, within 2 degrees of the equator.
The spots have been interpreted as the impact points of deorbiting ring material. Saturn, behind the rings and draped with their shadows, as seen by Cassini from a distance of , km.
Cassini image mosaic of the unlit side of the outer C Ring bottom and inner B Ring top near Saturn's equinox, showing multiple views of the shadow of Mimas. The shadow is attenuated by the denser B ring. The Maxwell Gap is below center. A spiral density wave in Saturn's inner B Ring which forms at a orbital resonance with Janus.
The wavelength decreases as the wave propagates away from the resonance, so the apparent foreshortening in the image is illusory. Dark B Ring spokes in a low- phase-angle Cassini image of the rings' unlit side. Left of center, two dark gaps the larger being the Huygens Gap and the bright from this viewing geometry ringlets to their left comprise the Cassini Division. Pan 's motion through the A ring 's Encke Gap induces edge waves and non-self-propagating spiraling wakes  ahead of and inward of it.
The other more tightly wound bands are spiral density waves. Radially stretched 4x view of the Keeler Gap edge waves induced by Daphnis. Prometheus at right and Pandora orbit just inside and outside the F Ring , but only Prometheus acts as a ring shepherd. Prometheus near apoapsis carving a dark channel in the F Ring with older channels to the right.
F ring dynamism, probably due to perturbing effects of small moonlets orbiting close to or through the ring's core. Saturn's shadow truncates the backlit G Ring and its bright inner arc. A video showing the arc's orbital motion may be viewed on YouTube  or the Cassini Imaging Team website.
Saturn and its A, B and C rings in visible and inset infrared light. In the false-color IR view, greater water ice content and larger grain size leads to blue-green color, while greater non-ice content and smaller grain size yields a reddish hue. From Wikipedia, the free encyclopedia.
Planar assemblage of icy particles orbiting Saturn. For other uses, see Rings of Saturn disambiguation. Saturn's rings and moons. Tethys, Hyperion and Prometheus. Tethys and Janus. High resolution about 3 km per pixel color view of the inner-central B Ring 98, to , km from Saturn's center. The structures shown from 40 km wide ringlets at center to — km wide bands at right remain sharply defined at scales below the resolution of the image. The B Ring's outer edge, viewed near equinox, where shadows are cast by vertical structures up to 2. The Cassini Division is at top. Play media.
The backlit E ring, with Enceladus silhouetted against it. The moon's south polar jets erupt brightly below it.
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Close-up of the south polar geysers of Enceladus, the source of the E Ring. E Ring tendrils from Enceladus geysers — comparison of images a, c with computer simulations. Main article: Rings of Rhea.
These encounters lead to periodic minor disruptions in the wave pattern. Retrieved In Kalas, P. Planets, Stars and Stellar Systems. Saturn Ring Plane Crossings of — Jet Propulsion Laboratory. Archived from the original on Sterling Publishing Company, Inc. Planetary Ring Systems. Springer Praxis Books in Space Exploration. The Planet Saturn. Quarterly Journal of the Royal Meteorological Society.
London: Faber and Faber Limited. April Beyond the Life Line. Astounding Stories. March Entry from Complete Dictionary of Scientific Biography". NASA web site. Solar System Exploration. Bibcode : Icar.. Bibcode : Icar The Atlantic. October Bulletin of the American Astronomical Society. Bibcode : DPS In Grun, E. Interplanetary Dust.
Berlin: Springer. Bibcode : indu. British Broadcasting Corporation. The Astrophysical Journal. Bibcode : ApJ Georgia Journal of Science. February Journal of the British Astronomical Association. British Astronomical Association.
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