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Definition of: planetarium
Our photo definition of planetarium 
(plan′ə·târ′ē·əm) noun plural ·tar·i·ums or ·tar·i·a
1. An apparatus for exhibiting the features of the heavens as they exist at any time and for any place on earth, consisting of a suitably mounted projector installed in a room having a circular dome.
2. An apparatus or model representing the planetary system. [<NL <LL planetarius PLANETARY]
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