Open star cluster M7, optical image. This cluster is sometimes called the Ptolemy cluster after the Greek astronomer who first recorded it in 130AD. The cluster lies around 1000 light years from Earth in the constellation Scorpius, and is thought to be about 220 million years old. It contains around 80 stars and is around 25 light years across. The darker areas at lower left and upper centre are dust clouds in the foreground, obscuring the light from behind.