• Alpha Canis Majoris, the brightest star in the night sky. Sirius has an apparent magnitude of –1.47 and an absolute magnitude of 1.45, and is 8.7 light years from Earth. The main star is of type A1, and is accompanied by a much smaller White Dwarf companion, Sirius B. There have been reports of other possible members of the Sirius system. Sirius is much the brightest star in Canis Major and is found by extending the line of the stars of Orion’s Belt south-westwards. Sirius is white and there have been numerous debates about whether its colour has changed in the last 2,000 years, since descriptions of its colour from antiquity, especially by Ptolemy, seem to refer to it as red. Translation difficulties and misunderstood astrological usages appear to be the explanation, not changes in the star itself.