In star clusters like M55 what is the average distance between them? They look all bunched together but I am curious to know just how close together they are.
Globular clusters like M55 are indeed very dense. As you may know the nearest other star system to our own is Alpha Centauri, about 4.2 light years away. In a globular cluster however the typical distance between stars is only 1 light year. In the centre the density is higher still, the typical distance between stars can be as little as a few hundred AU, comparable to the size of the solar system.