A planetarium is a show theatre constructed mainly to present entertaining and educational shows about the night sky and astronomy, or even to train in celestial navigation. The term planetaria is the plural of the planetarium. Most planetaria have a projection screen of a dome shape where scenes of planets, stars among other celestial elements are made to show and move in a realistic manner to stimulate the heavens' complex motions. These celestial scenes are designed using various technologies and these can be the star balls of the precision engineering which combine electromechanical and optical technology, lasers, full dome and video projector systems.

In this case, whatever type of technology used to create the scenes, its main objective is to link the scenes together to give an accurate relative sky movement.