Rings of Uranus one of which, Mab, shares its orbit with the outermost newly discovered μ ring. As currently understood, the ring system of Uranus comprises thirteen distinct rings. In order of increasing distance from the planet they are: 1986U2R/ζ, 6, 5, 4, α, β, η, γ, δ, λ, ε, ν, μ rings. They can be divided into three groups: nine narrow main rings (6, 5, 4, α, β, η, γ, δ, ε), two dusty rings (1986U2R/ζ, λ) and two outer rings (ν, μ). The rings of Uranus consist mainly of macroscopic particles and little dust, although dust is known to be present
Definition of planet in composition, size, and orbital characteristics. They concluded that they had discovered the long-hypothesised Kuiper belt (sometimes called the Edgeworth–Kuiper belt), a band of icy debris that is the source for "short-period" comets—those with orbital periods of up to 200 years. Pluto's orbit lay within this band and thus its planetary status was thrown into question. Many scientists concluded that tiny Pluto should be reclassified as a minor planet, just as Ceres had been a century earlier. Mike Brown of the California Institute of Technology suggested that a "planet" should be redefined as "any body in the Solar System that