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Betelgeuse, in the constellation Orion, is one of the brightest stars in the night sky and is the second-largest star in apparent size from our vantage point (not counting the sun, that is). Those attributes are made all the more impressive by the fact that Betelgeuse is some 650 light-years away—nowhere near cracking the list of the closest stars to our solar system.
Its brightness and size arise from the fact that the star is a red supergiant, a stage late in the life cycle of some stars in which they swell to great size. Estimates of Betelgeuse's physical size vary, but it is at least several hundred times the diameter of the sun.
Using observation data taken in 2005 at the now-defunct Infrared Optical Telescope Array in Arizona, Xavier Haubois and Guy Perrin of the Paris Observatory and their colleagues reconstructed an infrared image of the massive star. The researchers published their findings in December 2009 in Astronomy & Astrophysics. The highly detailed portrait revealed two bright spots on Betelgeuse of the kind that have long been known to swirl across the surface, two or three at a time. These spots could be markers of convection within the red supergiant, the authors report, and may trace the influence of Betelgeuse's magnetic field on its surface in much the same way that sunspots do on the sun.
