planetarium Meaning, Definition & Usage

  1. noun a building housing an instrument for projecting the positions of the planets onto a domed ceiling
  2. noun an optical device for projecting images of celestial bodies and other astronomical phenomena onto the inner surface of a hemispherical dome
  3. noun an apparatus or model for representing the solar systems

WordNet


Plan`e*ta"ri*um noun
Etymology
NL.: cf. F. planétaire. See Planetary.
Definitions
  1. An orrery. See Orrery. since the 1930's, orrery has retained its original meaning, but planetarium now refers primarily to a room with a dome-shaped roof, in which images of the night sky are projected from a central projector. The projector itself is also called a planetarium.

Webster 1913