An asterism is a pattern of stars that forms a recognizable shape in the night sky, but it is not officially classified as a constellation. Asterisms can be part of a larger constellation or stand alone. For example, the Big Dipper is an asterism within the constellation Ursa Major. Asterisms are often used by stargazers to help locate other celestial objects. They can be simple shapes, like the Summer Triangle, which consists of three bright stars from different constellations. Asterisms serve as helpful guides for both amateur and experienced astronomers when navigating the night sky.