Galaxy NGC 5866 is aligned to the Milky Way in a way that we can see it exactly edge-on. Many beautiful objects that we can observe in the universe are indeed thin discs: the rings of Saturn, protoplanetary discs and even entire galaxies. Just the definition of 'thin' is relative: whilst the rings of Saturn have a thickness of just 20 meters the thickness of a typical spiral galaxy like our Milky Way is about 1000 light years or 9.5 quadrillion km (or if you prefer: 9.5 quintillion meters)!