Starfield centred on the border between the constellations of Ophiucus (right) and Scorpius (left). The brightest star at centre left is Antares (alpha Scorpii), a red supergiant star 500 light years from the Earth. The red supergiant phase is one of the final stages in the life of a normal star. Antares has a surface temperature of 3100K and a mass 10-15 times the solar mass. It is seen embedded in a reflection nebula (IC 4606), a cloud of dust which reflects towards the Earth the radiation emitted by Antares and nearby stars. Two globular star clusters are seen in this frame: the smaller NGC 6144 is at centre left and the larger M4 at lower centre right.