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Noun: planetarium (planetariums,planetaria)  ,pla-ni'teh-ree-um
  1. A building housing an instrument for projecting the positions of the planets onto a domed ceiling
     
  2. An optical device for projecting images of celestial bodies and other astronomical phenomena onto the inner surface of a hemispherical dome
     
  3. An apparatus or model for representing the solar systems

Derived forms: planetaria, planetariums

Type of: building, edifice, model, optical device, simulation

Encyclopedia: Planetarium