On these cold winter nights, just a little southeast of Orion, is a dazzlingly bright star – the brightest one in the night sky. Officially called Alpha Canis Majoris (designating it as the brighest star in the constellation Canis Major), it is better known as Sirius or the Dog Star. While the intrinsic luminosity of Sirius is about 25 times that of the sun, much of it’s apparent brightness comes from it’s close proximity to our own solar system. At a distance of 8.6ly, it’s just down the street in interstellar terms.
Although it can’t be seen by the backyard astronomer, Sirius has a small white dwarf compainion star called Sirius B. Due to it’s brightness, Sirius itself often appears to twinkle more than most stars, often flashing a variety of colors. So if you see that bright star in the southern sky this winter, you know it is indeed Sirius.