The eleven rings around Uranus are thin bands some 0.6 to 7.0 miles (1 to 11 km) thick.
The exception is the farthest edge of the farthest ring, which ranges up to 60 miles (96 km).
The rings are composed of extremely dark particles, which vary in size from micrometers to a fraction of a meter.
They are made mostly of ice, with very little dust, the brightest being the ε ring.
Generally, rings occur as dust particles collide with each other within an orbit.
Astronomers could not figure out what had happened to the dust until Voyager studied Uranus’s atmosphere.
It turns out that the atmosphere extends higher up than expected, up into the rings.
The hydrogen in the atmosphere slows down the dust molecules, causing them to fall out of orbit.
This means that Uranus’s rings are disintegrating and, one day, will disappear.
