Nasa的解答是不在环面的颗粒因为轨道具有较高能量,但会因为互相碰撞损失能量坠入低能量的轨道面达到平衡。
贴一下原文和网址:
Why are Saturn's rings so thin? It has to do with the ring particles colliding with each other. Ring particles that are high above or below the rings are in a highly "inclined" (tilted) orbit, and have more energy than ring particles that are closer to the ring plane. When those particles collide with other particles, some of their energy is lost, so causing them to move to lower-energy orbits closer to the ring plane. Over time, the ring particles (especially the larger ones) tend to flatten themselves into a thin plane, as we see today. This is the general picture, but some of the details are still being worked out.
https://caps.gsfc.nasa.gov/simpson/kingswood/rings/ |