For generations, Betelgeuse has been one of the easiest stars to recognise in the night sky: a reddish point marking the shoulder of Orion, the Hunter. But behind that familiar glow is a huge, unstable star approaching the final stages of its life, and astronomers have now discovered that it has been hiding a stellar companion all along.
New observations with the European Southern Observatory's Very Large Telescope have produced the clearest evidence yet that Betelgeuse is part of a binary system. The finding could change how scientists understand the star's strange brightness variations, and may even complicate predictions about when it will eventually explode as a supernova.
