Saturn's rings do not clump into moons due to tidal forces within the Roche limit
the verdict
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refutedsupported
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AS REPORTEDno primary record reached; this is what the reporting says
While Britannica notes that the Roche limit involves tidal forces that can prevent ring material from forming moons, Science highlights that centimeter-sized particles do accrete into larger aggregates within the Roche zone.
Roche limit | Gravitational Effects, Tidal Forces & Orbital Stability | Britannica
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# Roche limit
astronomy
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Roche limit, in astronomy, the minimum distance to which a large satellite can approach its primary body without tidal forces overcoming the internal gravity holding the satellite together. If the satellite and the primary body are of similar composition, the theoretical limit is about 2 1/2 times the radius of the larger body. The rings of Saturn lie inside Saturn’s Roche limit and may be the debris of a demolished moon. The limit was first calculated by the French astronomerÉdouard Roche(1820–83). Artificial satellites are too small to develop substantial tidal stresses.
This article was most recently revised and updated by Erik Gregersen.
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Saturn Ring Particles as Dynamic Ephemeral Bodies | Science
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Contents
## Abstract
Although Saturn's rings are within the Roche zone, the accretion of centimeter-sized particles into large aggregates many meters in diameter occurs readily, on a time scale of weeks. These aggregates are disrupted when tidal stresses exceed their very low strengths; thus most of the mass of the ring system is continually processed through a population of large "dynamic ephemeral bodies," which are continually forming and disintegrating. These large aggregates are not at all like the idealized ice spheres often used in modeling Saturn's ring dynamics. Their coefficient of restitution is low, hence they form a monolayer in the ring plane. The optically observable characteristics of the rings are dominated by the swarm of centimeter-sized particles.
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## References
BRIDGES, F, unpublished data.
CHANDRASEKHAR, S, ELLIPSOIDAL FIGURES (1969).
CUZZI, J.N., VERTICAL STRUCTURE AND THICKNESS OF SATURNS RINGS, ICARUS 38: 54 (1979).
DAVIS, D.R., ASTEROIDS: 528 (1979).
DAVIS, D.R., THE UNUSUAL
Roche limit
A celestial body (yellow) is orbited by a mass of fluid (blue) held together by gravity, here viewed from above the orbital plane. Far from the Roche limit (white line), the mass is practically spherical.
Closer to the Roche limit, the body is deformed by tidal forces.
Within the Roche limit, the mass's own gravity can no longer withstand the tidal forces, and the body disintegrates.
Particles closer to the primary move more quickly than particles farther away, as represented by the red arrows.
The varying orbital speed of the material eventually causes it to form a ring.
In celestial mechanics, the Roche limit, also called Roche radius, is the distance from a celestial body within which a second celestial body, held together only by its own force of gravity, will disintegrate because the first body's tidal forces exceed the second body's self-gravitation. Inside the Roche limit, orbiting material disperses and forms rings, whereas outside the limit, material tends to coalesce. The Roche radius depends on the radius of the second body and on the ratio of the bodies' densities.
The term is named afterÉdouard Roche(French: [ʁɔʃ], English:/rɒʃ/ ROSH), the French ast
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