 A red supergiant, Betelgeuse is one of the largest and most luminous stars known.If it were at the center of our Solar System its surface would extend past the asteroid belt, possibly to the orbit of Jupiter or even beyond, wholly engulfing Mercury, Venus, Earth and Mars.Classified as an M-type supergiant star, and located around 640 light-years from Earth, Betelgeuse shares with the much closer but smaller star Altair (and with R Doradus) the distinction that its image has been resolved by astronomers (see graphic).