From our point of view on Earth, the Milky Way forms a belt of pale light that wraps around the sky, passing through familiar constellations such as Cassiopeia and Cygnus in the northern sky and the Southern Cross and Carina in the far south. Ancient Greek stargazers imagined it as a stream of milk spilt by Hera, queen of the gods, and named it ‘galaxias kyklos’, the Milky Circle. Later, Roman astronomers translated this to via lactea, the Milky Way.