Jupiter’s rings were discovered by Voyager 1 in a single image that was targeted specifically to search for a possible ring system. Voyager 2 was reprogrammed en route to take a more complete set of pictures. The image above is from that series. We now known that the system has three major components. The Main ring is about 7,000 km wide and has an abrupt outer boundary roughly 129,000 km from the center of the planet. This ring encompasses the orbits of two small moons, Adrastea and Metis, which probably are the source for the material that makes up most of the ring. The main ring merges gradually into the Halo on the side toward Jupiter. The halo is a broad, faint, donut of material about 20,000 km thick and extending halfway from the main ring down to the planet’s cloudtops.
Around the main ring is the broad and exceedingly faint Gossamer ring. It extends out beyond the orbit of the moon Amalthea and is probably composed of dust particles less than 10 µm in diameter. That’s roughly the size of cigarette smoke particles. It extends to an outer edge of about 129,000 km from the center of the planet and inward to about 30,000 km. The origin of the ring is probably material knocked loose by micrometeorite bombardment of the tiny moons orbiting within the ring.
Jupiter’s rings and moons exist within an intense radiation belt of electrons and ions trapped in the planet’s magnetic field. These particles and fields make up the Jovian magnetosphere or magnetic environment which extends up to 7 million km toward the Sun and stretches outward 750 million km in a windsock shape to Saturn’s orbit.
Image Credit: NASA