An asterism is an observed pattern or group of stars in the sky. Constellations are based on asterisms, but asterisms can be any pattern or group of stars. They are a more general concept than the 88 constellations of the IAU. Several countries use these patterns in their flags.
- The area of the southern cross is known as the constellation Crux. In this case the asterism and the constellation are more or less the same thing.
- The Big Dipper, also known as The Plough, is made of the seven brightest stars in Ursa Major. It is certainly the best-known asterism in the Northern Hemisphere.