Astronomers using the Keck 10 metre telescope have discovered a dwarf galaxy 10 billion light years away, making it the most distant dwarf galaxy every discovered. The dwarf galaxy is a satellite of a much bigger elliptical galaxy, and was detected through a technique called gravitational lensing. Light from a more distant galaxy behind the elliptical is bent around the elliptical galaxy. The light from the source galaxy is then magnified and deformed into the shape of a ring, and the “lensing” elliptical galaxy is seen in the centre of the picture. While the dwarf galaxy which orbits the elliptical cannot be imaged directly, it was detected due to the effect it has on the overall mass of the system.