Rayleigh-Taylor instability

A Rayleigh-Taylor instability is a type of fluid instability that occurs any time a dense, heavy fluid is being accelerated by light fluid. Rayleigh-Taylor instabilities are common in supernova remnants, such as the Crab Nebula, in which hot gas from the explosion is ramming into the surrounding interstellar medium, and they give rise to the familiar clumpy appearance of material in these objects.