Starwatch: Sirius, the dog star, rises to brighten winter nights

There’s a treat in store all week for early risers. Sirius, the brightest star in the night sky, will be glittering in the southern sky in the pre-dawn hours. Having been absent from view for several months, the star is now rising shortly after midnight. Located just 8.6 light years away, Sirius is about twice the mass of the sun and 25 times more luminous. It makes for an unmistakable sight, twinkling and sparkling in the night sky. The chart shows the view looking due south at 06:00 GMT on 22 October. Sirius is part of the constellation Canis Major, the great dog, and Sirius itself is sometime called the dog star. The star formed an important part of ancient Egyptian religious beliefs, and used to be visible during the Egyptian summer. The supposed heat from Sirius was thought to combine with the sun’s rays to give the country its soaring summer temperatures. This is where the expression the dog days of summer comes from.