Groups of stars that are visible in definite patterns are called Constellations. Ursa Major (the Big Bear), The Small Bear (Saptarishi), etc. are some well-known constellations.
Constellations have been named after legendary heroes or called after familiar forms and animals. Some names like Corona Boreaiis (the Northern Crown), Cygnus (the Swan) and the seven stars in Ursa Major, known as the Plough, bear some resemblance to the figures of things they are suppose to represent.
There are two types of star groups:
- Open or Galactic Clusters are groups of up to two or three hundred stars which are found in the spirals of the Milky Way.
- Globular Clusters contain over one hundred thousand stars and represent the outer stellar population of Milky Way.