Scott Tremaine, “Astrophysical Wonders” (Open Agenda, 2021)
New Books in Science, Technology, and Society
00:00
Is There a Gap in the Rings?
There is a gap in saturn's rings called the cassina gap, discovered by cassina not long after galileo first discovered the rings. The problem was that these rings were typically only a few kilometers across. And if you have something in orbit that's losing energy, but serving its angit momentum, it has to spread out. That means that any disc around a planet should always spread out. If there's a gap in the rings, the rings should spread out and fill it in. There's just no way that a ring that's narrow shouldn't spread out and become less diffuse than the age of saturn.
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