dipper@utastro.UUCP (Debbie Byrd) (05/24/85)
The rings of Uranus are narrow and dark. More on planetary rings -- after this. May 24 Eight Months to Uranus The remote planet Uranus soon will become more familiar -- because the Voyager spacecraft soon will encounter Uranus -- with its closest approach eight months from today. We don't know what Voyager will find in the vicinity of Uranus. But, among other things, Voyager will look at the planet's rings, discovered in 1977. Uranus, Saturn and Jupiter all have rings. The rings in each case consist of separate particles -- small moonlets -- moving in a band around the three worlds. But the three ring systems are very different. For example, Saturn's rings are broad and bright -- made of ice. Jupiter's ring is faint -- the faintest of the three -- and probably consists of bits of rocky dust or dirty ice. The rings of Uranus are brighter than Jupiter's ring -- but still pretty dark. They're probably rocky, too, rather than icy. What's more, the number and spacing of the rings are different for each world. A thousand or more rings encircle Saturn -- narrow ringlets separated by narrow gaps. Jupiter's ring isn't as wide overall -- it may consist of smaller ringlets, too, although that's not yet known. But the rings of Uranus appear definitely separate. They're very narrow -- with wide gaps between each ring. There are at least nine rings encircling Uranus. It's possible that small undiscovered moons move within the system of uranian rings. If so, the Voyager spacecraft may discover these unknown moons -- when it gets to Uranus eight months from today. Script by Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin