Arcturus (α Boo / α Boötis / Alpha Boötis) is the brightest star in the constellation Boötes, and the third brightest star in the night sky, with a visual magnitude of −0.05, after Sirius and Canopus. Because Alpha Centauri consists of two bright stars which are closer together than the limit of resolution of the human eye, Alpha Centauri actually appears brighter than Arcturus to the naked eye. It is the second brightest star visible from northern latitudes and the brightest star in the northern celestial hemisphere.