Sirius
Sirius.Sirius, designated Alpha Canis Majoris, is the brightest star in the night sky with a visual magnitude of −1.46. It is a close binary star system, consisting of Sirius A, a white main-sequence star, and a faint companion white dwarf, Sirius B, which was originally a massive bluish star that became a red giant before shedding its outer layers and collapsing to a white dwarf. It is one of Earth's near neighbors, at 2.6 parsecs (8.6 light-years). Sirius A is about twice as massive as the Sun and has an absolute magnitude of 1.42. It is 25 times more luminous than the Sun but has a lower luminosity than other bright stars. The system is 200 to 300 million years old. Sirius is known as the "Dog Star", due to its prominence in its constellation, Canis Major. The 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 was important for Pacific navigation.