Illustration of the binary star system of Sirius A and smaller companion, Sirius B. The large, bluish-white star Sirius A dominates the scene, while Sirius B is the small but very hot and blue white-dwarf star at right. The two stars revolve around each other every 50 years. White dwarfs are the leftover remnants of stars similar to our Sun. The Sirius system, at 8.6 light-years from Earth, is the fifth closest stellar system known. Sirius B is faint because of its tiny size. Its diameter is only about 12 thousand kilometres, slightly smaller than the size of Earth. The Sirius system is so close to Earth that most of the familiar constellations would have nearly the same appearance as in our own sky. In the background are the three bright stars that make up the Summer Triangle: Altair, Deneb, and Vega. Our own Sun is the second-magnitude star, shown as a small dot just below and to the right of Sirius A.