Sirius is the brightest star in the night sky. With a visual apparent magnitude of −1.46, it is almost twice as bright as Canopus, the next brightest star. The name "Sirius" is derived from the Ancient Greek Σείριος Seirios ("scorcher"). What the naked eye perceives as a single star is actually a binary star system, consisting of a white main sequence star of spectral type A1V, termed Sirius A , and a faint white dwarf companion of spectral type DA2, termed Sirius B . The distance separating Sirius A from its companion varies between 8.1 and 31.5 AU. Sirius appears bright because of both its intrinsic lumosity and its proximity to Earth. Sirius is also known colloquially as the " Dog Star ", reflecting its prominence in its constellation, Canis Major (Big Dog). The heliacal rising of Sirius marked the flooding of the Nile in Ancient Egypt and the "Dog days" of summer for the Ancient Greeks, while to the Polynesians it marked winter a...