Why do some planets have rings? What are they made of? The rings of Jupiter, Uranus, and Nep- tune are made of dust, very tiny pieces of rock, and ice. The rings of Saturn are made of large pieces of ice. We don't know for sure where these rings came from. In some cases, the rings have come from dust knocked off of the planets' moons by meteorite bom- bardment, but some of them might have come from moons torn apart by the plan- et's gravity, or they could have formed as the planets formed. Saturn's rings are the most magnifi- cent; they are bright, wide, and colourful. Uranus has thirteen dark rings around it, and Neptune's rings are also dark, but contain a few bright arcs.