This busy image is a treasure trove of wonders. Bright stars from the Milky Way sparkle in the foreground, the magnificent swirls of several spiral galaxies are visible across the frame, and a glowing assortment of objects at the center makes up a massive galaxy cluster. Such clusters are the biggest objects in the universe that are held together by gravity and can contain thousands of galaxies of all shapes and sizes. Typically, they have a mass of about one million billion times the mass of the Sun—unimaginably huge!