One of a pair of stars in a binary system, Sirius B orbits its sister, Sirius A, approximately 8.6 light years from Earth. While Sirius A is the brightest star in our night sky, B is 10,000 times dimmer, and for this reason was not discovered until 1862, by Alvan Clark.
Sirius B is a white dwarf star with a mass equal to that of our Sun, but a diameter less than that of the Earth. This means that the force of gravity on its surface is 400,000 times that which human beings feel. Because of its lesser mass (Sirius A is approximately twice as massive as the Sun), Sirius B orbits its larger sister once every 50 years.
Some controversy surrounds the knowledge that a certain tribe in Timbuktu, the Dogon, were discovered to have about the Sirius star system, and particularly Sirius B. When the Dogon were visited by French anthropologists in the late 1940's, they demonstrated advanced knowledge about this white dwarf star that should have been completely invisible to them, including the length of its orbit. Further information on this strange story can be found under Dogon or in Robert Temple's book, The Sirius Mystery: New Scientific Evidence for Alien Contact 5,000 Years Ago