who discovered it?
James L. Elliot, Edward W. Dunham, and Jessica Mink.
Rings of Uranus
The rings of Uranus were discovered on March 10, 1977, by James L. Elliot, Edward W. Dunham, and Jessica Mink. 
what is rings of uranus? Are intermediate in complexity between the more extensive set around Saturn and the simpler systems around Jupiter and Neptune. how many rings does this planet have? 13 when was the first time it was discovered? 1978
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Rings of Uranus [SEP] Introduction
The rings of Uranus are 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 Jessica Mink. William Herschel had also reported observing rings in 1789; modern astronomers are divided on whether he could have seen them, as they are very dark and faint. By 1978, nine distinct rings were identified. 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.