Why do planets have rings? What are they made of?
The rings of Jupiter are made of dust, which probably was knocked off of its moons by meteorite impacts.
The rings of Saturn are made of chunks of water ice, mostly about 2 centimeters in size, the size of a baseball or softball. The rings of Uranus are made of larger ice boulders several meters across, and quite a bit of dust. The rings of Uranus are made of darker stuff than Saturn's rings, probably dirtier ice. We don't know for sure where the rings of Uranus and Saturn came from. Some of the rings might come from moons torn apart by the planet's gravity, or they could have formed as the planets formed.
Neptune's rings are even more mysterious. We don't have a good idea of what they're made of, but the ring particles are probably very small, dark particles of ice and rock.
This page was last updated June 28, 2015.