The planet
Uranus has a system of
ring intermediate in complexity between the more extensive set around
Saturn and the simpler systems around
Jupiter and
Neptune. The
rings of Uranus were discovered on March 10, 1977, by
James L. Elliot, Edward W. Dunham, and
Douglas J. Mink. More than 200 years ago,
William Herschel also reported observing rings, but modern astronomers are skeptical that he could have actually seen them, as they are very dark and faint. Two additional rings were discovered in 1986 in images taken by the
Voyager 2 spacecraft, and two outer rings were found in 2003–2005 in
Hubble Space Telescope photos.
the Uranian ring system is known to consist of 13 distinct rings. In the order of increasing distance from the planet they are designated 1986U2R/
ζ, 6, 5, 4,
α,
β,
η,
γ,
δ,
λ,
ε,
ν and
μ. Their radii range from about 38,000 km for the 1986U2R/ζ ring to about 98,000 km for the μ ring. Additional faint dust bands and incomplete arcs may exist between the main rings. The rings are extremely dark—the
Bond albedo of the rings' particles does not exceed 2%. They are probably composed of water ice with the addition of some dark radiation-processed
organics.
The majority of Uranus's rings are opaque and only a few kilometers wide. The ring system contains little dust overall; it consists mostly of large bodies 0.2–20 m in diameter. However, some rings are optically thin: the broad and faint...
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