Two large spiral galaxies can be seen colliding with each other in this picture. Both galaxies are similar in size and shape to the Milky Way. Surrounding them is a"halo" of material. A halo is one of five key features that make up all galaxies, along with the 'nucleus', sitting right at the heart of a galaxy, the 'disc', which contains a large bulk of the galaxy's material, the invisible 'magnetic field', and a second halo of ‘dark matter’.
X-ray (NASA/CXC/SAO/E.Nardini et al); Optical (NASA/STScI)