a building housing an instrument for projecting the positions of the planets onto a domed ceiling
"We spent the evening inside the planetarium watching stars and planets project across its domed ceiling."
an optical device for projecting images of celestial bodies and other astronomical phenomena onto the inner surface of a hemispherical dome
"The children gasped in wonder as the planetarium projected swirling nebulas across the domed ceiling, making them feel like they were floating among the stars."
an apparatus or model for representing the solar systems
"The museum's planetarium used a rotating globe to demonstrate how the planets orbit the sun."
A display museum in which images of stars and other astronomical phenomena are projected onto a domed ceiling.
"The family spent their summer evening at the planetarium, where the dome above them transformed into a swirling galaxy of projected stars and nebulas."