The Emu is a constellation known to many Aboriginal groups in Australia. It is not a constellation in the usual sense, because it is defined by areas of dark shadow between the bands of the Milky Way (caused by dust and gas clouds in space), rather than by stars. The emu's head is the very dark Coalsack nebula, next to the Southern Cross. The body and legs are other dark clouds trailing out along the Milky Way and across the Scorpius constellation.