Canopus , or Alpha Carinae in the Bayer designation system is the brightest star in its constellation ( Canopus ) and the brightest star in the southern night sky . Canopus ( Î Car , Î Carinae , Alpha Carinae ) is the brightest star in the southern constellation of Carina and Argo Navis , and the second brightest star in the night-time sky , after Sirius . Canopus 's visual magnitude is 0.72 , and it has an absolute magnitude of 5.53 .