In an image akin to the Hubble Deep Field, ESO's La Silla Observatory in Chile stared at a patch of sky about as big as a full Moon and observed thousands of distant galaxies. The Wide Field Imager on ESO's 2.2 meter telescope zeroed in on a large group of galaxies that are part of the massive galaxy cluster known as Abell 315. But there's more in this image—including relatively close asteroids that show up as blue, green or red trails, which lie in the main asteroid belt, located between the orbits of Mars and Jupiter. Also, invisible dark matter is revealed in this image through its gravitational effects, noticeably visible on this galaxy cluster.