Sirius. Optical image of the star Sirius, the brightest star in the sky, with the exception of the Sun. North is at top. Sirius (Alpha Canis Majoris), also known as the Dog Star, lies in the constellation of Canis Major. It has a visual magnitude of -1.46. It is itself a fairly average star, however, and only appears so bright due to its proximity to Earth. It lies around 8.6 light years away, making it the 9th nearest star to the Sun. Sirius is actually a double star. It has a very faint companion, Sirius B, which is a white dwarf. Sirius itself has the spectral class A1, meaning it is a very hot white star, with a surface temperature around 10,000 degrees Celsius.