Southern cross. Optical image of the constellation Crux, the southern cross (centre right). North is at top. The dark patch just below centre is called the Coal Sack. It is a nearby dark nebula which obscures the light of the bright Milky Way behind it. The bright star at the left of the cross, just above the Coal Sack, is Mimosa (Beta Crucis). To the right of the Coal Sack, at the foot of the cross, is Acrux (Alpha Crucis). The bright star at far left is Hadar (Beta Centauri) in the neighbouring constellation Centaurus, the centaur. Crux is best seen in autumn from the southern hemisphere.