An asterism is a pattern or group of stars in the night sky that is not officially recognized as a constellation, but is still notable for its distinctive shape. These groupings are often part of larger constellations or are simply informal groupings that are easy to spot.
A classic example of an asterism is the Big Dipper, which is part of the constellation Ursa Major. Another well-known one is the Summer Triangle, formed by the stars Vega, Deneb, and Altair from different constellations.
Asterisms are often used by stargazers to help navigate the sky and identify constellations or other celestial objects.