What are Jupiter's rings primarily composed of?

Jupiter’s rings are primarily composed of dust. Unlike Saturn’s bright rings, which are dominated by water ice, Jupiter’s rings are made mostly of fine, dark particles and are extremely faint when viewed from Earth.

The ring system was discovered by Voyager 1 in 1979 when the spacecraft looked back toward Jupiter with the Sun behind the planet. This backlighting made the thin rings visible. Later observations by NASA’s Galileo spacecraft helped explain where the material comes from: micrometeoroids strike Jupiter’s small inner moons and blast dust from their surfaces into orbit.

The main ring is associated mainly with debris from the moons Metis and Adrastea. Thebe and Amalthea supply material for the broader gossamer rings. Jupiter’s strong gravity and magnetic environment continually affect these tiny particles, while some dust eventually falls into the planet’s atmosphere or settles onto nearby moons.

The main mix-up is assuming every planetary ring system is icy. Jupiter’s rings contain little obvious ice compared with Saturn’s and are better described as a faint, dusty debris system.