Galactic corona

A galactic corona is something that is found around a galaxy. It is made up of a cloud of particles, or tiny pieces of matter, that are mostly hydrogen and helium. This corona is very hot, at temperatures of millions of degrees. It's so hot that it gives off X-ray radiation, or 'X-ray light' that you can see in pictures taken with special telescopes. Also, magnetic fields in the corona keep everything in its place, like walls around the galaxy.