Don Lincoln This time, Cerenkov tries to generate radiation. This is the case when the body is much lighter than in the middle.
It's not a purely academic. This is how we find certain particles like neutrinos. These photodetectors, say SuperKamiokande, reveal this Cerenkov radiation. In fact, if we see nuclear fuel in water, the blue light is Cerenkov radiation.
Here is a chance to learn about the radiation of Kerintsov.