In 1859, James Clerk Maxwell demonstrated that a nonuniform solid ring, solid ringlets or a continuous fluid ring would also not be stable, indicating that the ring must be composed of numerous small particles, all independently orbiting Saturn. [58][59][60] For half of a Saturn year, the ringed planet appears to bow toward the sun, which then illuminates the top of the rings. That may sound like a whole lot.

[36] The rings also have a similarly sparse OH (hydroxide) atmosphere. While the traditional view has been that it is held together by two shepherd moons, Prometheus and Pandora, which orbit inside and outside it,[89] recent studies indicate that only Prometheus contributes to the confinement. The material in the arc is believed to represent dust ejected from Methone by micrometeoroid impacts. Kristen Erickson The ring particles are made almost entirely of water ice, with a trace component of rocky material. "[5] He also described the rings as Saturn's "ears". Whether you're doing it for the nerd cred or the pie, this week on #10Things, we've got all the ways you can celebrate #PiDay with NASA. may be clouds of electrified dust rotating around [4][9] Robert Hooke was another early observer of the rings of Saturn, and noted the casting of shadows on the rings. It is primarily acted on by the 7:6 resonance with Janus and Epimetheus, with other contributions from the 5:3 resonance with Mimas and various resonances with Prometheus and Pandora. Better and better telescopes helped reveal that the rings were really a system of particles, and Jean-Dominique Cassini discovered 4 other major moons of Saturn: Iapetus, Rhea, Tethys and Dione. Because he happened to be viewing their edge, he failed to recognize them as rings. Eventually, they’ll essentially fade away. stable. [107][108] Numerical simulations suggest the ring was formed when Prometheus and Pandora collided with each other and were partially disrupted. The Great Tours: England, Scotland, and Wales, “Voyager 2” Sends Messages from Interstellar Space with Minimal Signal. * Two small moons, one on each side of the F-ring, So if researchers know how fast the color and mass and brightness of the rings should be changing, and they know what they look like now — that’s a pretty good starting point for estimating their age. [citation needed], A more traditional version of the disrupted-moon theory is that the rings are composed of debris from a moon 400 to 600 km in diameter, slightly larger than Mimas. Cassini watched some of Saturn’s moons steal ring particles, and other moons contribute particles to the rings.​.

Voyager 1 followed in November 1980, sending back breathtaking photographs that revealed for the first time the complexities of Saturn's ring system and moons. Cassini scientists have found the ingredients for amino acids condensed onto ice grains emitted by Saturn's sixth-largest moon. We also know they’re made of almost entirely ice — about 95 percent pure water ice, with another 5 percent rock and metals. [82] The resonance causes Mimas' pulls on these ring particles to accumulate, destabilizing their orbits and leading to a sharp cutoff in ring density. JPL has won an Emmy Award for Outstanding Original Interactive Program for its coverage of the Cassini mission's Grand Finale at Saturn. Rhea would then be the oldest of the moons formed from the primordial rings, with moons closer to Saturn being progressively younger. — Not with a Message, But with a Molecule, Astronomers Spy Phosphine on Venus, a Potential Sign of Life, Watch Out: Objects in the Universe are Bigger than They Appear. Using the Pic du Midi Observatory, Dollfus is able to establish the actual edge-on brightness of the rings, and estimates the thickness of the rings at only 2.4 km. They might be meteoroid impacts into the rings or even lightning bolts in Saturn’s atmosphere. The rings of Saturn were first discovered in 1610 by Italian astronomer, Galileo Galilei. From an average distance of 886 million miles (1.4 billion kilometers), Saturn is 9.5 astronomical units away from the Sun.

[7], In 1657 Christopher Wren became Professor of Astronomy at Gresham College, London. Unable either to form into a moon or to drift away from each other, individual ring particles appear to be held in place by the gravitational pull of Saturn and its satellites. above absolute zero. However, new research indicates that the B Ring may be massive enough to have diluted infalling material and thus avoided substantial darkening over the age of the Solar System. Mystified, Galileo remarked "I do not know what to say in a case so surprising, so unlooked for and so novel. * Although lightning bolts were not observed on

of the Moon and Mercury, although Saturn's [109], More recent closeup images from the Cassini probe show that the F Ring consists of one core ring and a spiral strand around it. SCIENCE FICTION SPACE TECHNOLOGY HOME PAGE. large A-ring, likewise may help keep that ring in In 1980, the Voyager 1 mission first observed the ‘spokes’. The radial width of the arc is about 250 km, compared to a width of 9,000 km for the G Ring as a whole. Cassini Discovers Possible Rings at Rhea", "Another possible piece of evidence for a Rhea ring", http://photojournal.jpl.nasa.gov/catalog/PIA09883, "Soft Collision (NASA Cassini Saturn Mission Images)", "Rounding the Corner (NASA Cassini Saturn Mission Images)", Planetary Rings Node: Saturn's Ring System, Biggest Ring Around Saturn Just Got Supersized, Everything a Curious Mind Should Know About Planetary Ring Systems with Dr Mark Showalter, Dialogue Concerning the Two Chief World Systems, Mathematical and physical investigations of properties of the pendulum, conception of centrifugal and centripetal forces, List of things named after Christiaan Huygens, Revolution in Time: Clocks and the Making of the Modern World, Golden Age of Dutch science and technology, Science and technology in the Dutch Republic, https://en.wikipedia.org/w/index.php?title=Rings_of_Saturn&oldid=980284243, Articles with unsourced statements from July 2008, Creative Commons Attribution-ShareAlike License, This page was last edited on 25 September 2020, at 16:52. Immediately Wren recognised this as a better hypothesis than his own and De corpore saturni was never published.

[44][45], There are two main theories regarding the origin of Saturn's inner rings. It was discovered in 1675 by Giovanni Cassini at the Paris Observatory using a refracting telescope that had a 2.5-inch objective lens with a 20-foot-long focal length and a 90x magnification. William Lassell termed it the "Crepe Ring" because it seemed to be composed of darker material than the brighter A and B Rings.[69]. theory. The Cassini mission revealed a surprising feature emerging at Saturn's northern pole as it nears summertime: a warming, high-altitude vortex with a hexagonal shape, akin to the famous hexagon seen deeper down in Saturn's clouds. Mimas is marked by a huge

[113] The arc is thought to contain matter equivalent to a small icy moonlet about a hundred m in diameter. The following week was dedicated to PSG #75, the Cassini Project Science Group meeting at JPL. [129] The ring was subsequently studied using the WISE, Herschel and Cassini spacecraft;[130] WISE observations show that it extends from at least between 50 and 100 to 270 Saturn radii (the inner edge is lost in the planet's glare). [116][117] Under the influence of the same resonance, Methone librates back and forth in its orbit with an amplitude of 5° of longitude. discovered around Saturn: Epimetheusby Stephen Larson, John Fountain and R. Walker, and Janusby Audouin Dollfus. He had been making observations of the planet Saturn from around 1652 with the aim of explaining its appearance. Prometheus near apoapsis carving a dark channel in the F Ring (with older channels to the right). Galileo correctly predicted that they would return.