Narrator: Listen to part of a lecture in an astronomy class. Professor: Now, we've all heard about the rings of Saturn, but Jupiter also has rings, though they're much fainter and were only discovered in 1979 by the Voyager 1 spacecraft. Unlike Saturn's bright, icy rings, Jupiter's rings are composed mostly of tiny dust particles. These particles are likely knocked off the surfaces of small inner moons by meteoroid impacts. The dust then spirals inward toward Jupiter due to gravitational and electromagnetic forces. Interestingly, the main ring is quite thin, only about 30 kilometers thick, but it extends tens of thousands of kilometers from the planet. There's also a faint, thick halo and a gossamer ring that extends even farther. The Galileo spacecraft later provided detailed images, confirming that the ring system is dynamic, with material constantly being added and removed. So, when we think of planetary rings, we shouldn't assume they're all like Saturn's.
❓ 题目 According to the professor, what is a key difference between Jupiter's rings and Saturn's rings?
A. Jupiter's rings are brighter and mostly made of ice.
B. Jupiter's rings are fainter and composed mostly of dust particles.
C. Jupiter's rings were discovered much earlier than Saturn's.
D. Jupiter's rings are static and have no changes.
✅ 正确答案
Jupiter's rings are fainter and composed mostly of dust particles.
