By then, 11″ will lie between Sirius A and Sirius B, also known as the Pup (because Sirius is the Dog Star). After that, the separation will close until 2043, when it will measure only 2.5″.

Sirius B, the accompanying white dwarf to A-class Sirius, used to be the dominant star, but it’s 10,000 times fainter now and difficult to see (as is Procyon’s companion).

Sirius, in the constellation Canis Major, shines at magnitude -1.46, so has long been a well-known star to many ancient cultures. It’s the fifth-closest star system to our own.