Solar System -
Jupiter
It is not well known that Jupiter has a faint ring system, but nothing like as spectacular as Saturn's. The Voyager 1 spacecraft first identified the rings in 1979. The ring system is made up of dust particles that resemble dark red soot, unlike Saturn's rings that are predominantly ice. The Jupiter ring comprises three major components.
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Closest to the planet, the halo is a faint torus about 30,500 km (19,000 miles) wide, and 12,500 km (7,750 miles) thick. It starts just above the clouds, about 92,000 km (57,000 miles) from the planet's center, and merges into the main ring at its outer edge.
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The main ring is about 6,750 km (4,200 miles) wide & reaches from the halo to 129,130 km (80,240 miles) from the center of the planet, with a pronounced outer boundary. The two moons Adrastea & Metis orbit Jupiter within the ring, and they may cause the dust that makes up most of the ring. The inner edge of the ring merges into the halo. The density of the surface of the main ring is about 5 millionths of a gram/square cm; this is very tenuous.
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Finally, outside the main ring, lies the gossamer ring. This is very tenuous comprising particles about the same size as smoke particles, which extends out beyond the orbit of the moon Amalthea. In fact, this ring is in two parts:
1. the inner Amalthea Gossamer Ring starts at a radius of about 129,200 km with its outer
edge at 182,000 km.
2. the outer Thebe Gossamer Ring, that seems to extend inwards to enclose the Amalthea
ring, starts at a radius of about 182,000 km with its outer edge at 224,900 km.
1. the inner Amalthea Gossamer Ring starts at a radius of about 129,200 km with its outer
edge at 182,000 km.
2. the outer Thebe Gossamer Ring, that seems to extend inwards to enclose the Amalthea
ring, starts at a radius of about 182,000 km with its outer edge at 224,900 km.
Credit: NASA/JPL/Cornell University
Jupiter's Rings
Jupiter's strong gravitational field attracts meteorites and fragments of comets and asteroids, some of which strike the four inner moons. The object buries itself into the moon, then vaporizes and explodes, causing material to fly off at such high velocity that it escapes the weak gravity of the moon. The Galileo probe photographed dust coming from Amalthea and Thebe. The gravitational pull of the very small moons is not sufficient to stop the dust. The dust then starts to orbit Jupiter and becomes part of the ring system. Amalthea and Thebe feed the two gossamer rings, while Adrastea and Metis are thought to feed the halo ring and the main ring.
Dust from the rings is constantly pulled down into Jupiter. One estimate is that it takes about 14 days from the time dust enters the halo for it to fall into Jupiter. If the rings were not replenished by more impacts on the moons, they would eventually disappear.
Dust from the rings is constantly pulled down into Jupiter. One estimate is that it takes about 14 days from the time dust enters the halo for it to fall into Jupiter. If the rings were not replenished by more impacts on the moons, they would eventually disappear.
An image of Jupiters rings taken by Voyager 2. Image includes credit & description.
Click to enlarge
