The greatest apparent magnitude of Venus at any particular apparition. It depends on both the planet’s distance and its phase. Venus varies greatly in apparent size; at superior conjunction, its disk is fully illuminated but its diameter is only 10″, whereas at inferior conjunction it is over 60″ in diameter but it is a very thin crescent. Its brightness increases as it moves away from superior conjunction, because of the increasing apparent area of the illuminated disk, but eventually the rapidly thinning crescent counteracts the increase in apparent diameter, and the magnitude starts to fall again. Greatest brilliancy occurs about 36 days before and after inferior conjunction, when Venus is the brightest object in the sky after the Sun and Moon, reaching up to magnitude −4.7.