An asterism is a distinctive pattern of stars in the sky but not including
any of the 88 recognized constellations.
Asterisms that form part of a single constellations include the Big
Dipper (part of Ursa Major), the Northern
Cross (part of Cygnus), the Square
of Pegasus, Orion's Belt, the Sickle
(part of Leo), the Teapot (part of Sagittarius), and the "W" or "M" of Cassiopeia.
Asterisms whose stars lie in more than one constellation include the Summer
Triangle, the Winter Triangle,
and the Winter Hexagon.