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Noun: planetarium (planetariums,planetaria)  ,pla-ni'teh-ree-um
  1. An optical device for projecting images of celestial bodies and other astronomical phenomena onto the inner surface of a hemispherical dome
    "The new planetarium projector could simulate the night sky with incredible accuracy"
     
  2. A building housing an instrument for projecting the positions of the planets onto a domed ceiling
    "We visited the planetarium to watch a show about black holes"
     
  3. An apparatus or model for representing the solar system
    "The children were fascinated by the miniature planetarium in the science museum"

Derived forms: planetaria, planetariums

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

Encyclopedia: Planetarium