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Many of you by know probably know what the Roche Limit is, if not, then here is a quick definition. The Roche Limit is the minimum distance from a parent body a satellite can orbit without being pulled apart by tidal forces. What this means is that if, for instance, the moon were to decay into an orbit within its Earth-Moon Roche Limit, it would be torn apart by Earth's gravity and be turned into rings (kinda like Saturn). For me, this is where the confusion starts. I've seen two different formulae regarding the Roche Limit and they are (in terms of mass): Rigid Satellite: d = 1.26Rm(MM/Mm)^1/3 Fluid Satellite: d ~= 2.44Rm(MM/Mm)^1/3 d = distance, Rm = radius of satellite, MM = mass of parent, Mm = mass of satellite Now, first of all, I realize that the Moon acts as a fluid satellite rather than a rigid one; no idea as to why though. The thing that interests me the most after running the numbers to discover that the Earth-Moon Roche Limit is ~18,500km is the question; what would the thickness of the ring be? My initial instinct would be that the inner limit of the ring would be defined by the first equation I provided while the outer limit would be defined by the second. Nevertheless,I'm sure that all you smarty-pants people will be able to figure this out, but also let me know if there is something that I'm missing or anything I got wrong. This is literally all I know about the Roche Limit .