planetarium

American  

[plan-i-tair-ee-uhm] / ˌplæn ɪˈtɛər i əm /

noun

• planetariums,
  plural
• planetaria
  plural

1. an apparatus or model representing the planetary system.

2. a device that produces a representation of the heavens by the use of a number of moving projectors.

3. the building or room in which such a device is housed.

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planetarium British  

/ ˌplænɪˈtɛərɪəm /

noun

1. an instrument for simulating the apparent motions of the sun, moon, and planets against a background of stars by projecting images of these bodies onto the inside of a domed ceiling

2. a building in which such an instrument is housed

3. a model of the solar system, sometimes mechanized to show the relative motions of the planets

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Other Word Forms

Noun Inflected Forms

• planetaria
  plural
• planetariums
  plural

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Etymology

Origin of planetarium

1765–75; < New Latin, noun use of neuter of Latin planētārius planetary; cf. -arium

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Explanation

A planetarium is a theater where you can look at images of planets, stars, and other celestial bodies on the dome-shaped ceiling. Planetariums host school field trips by day, and can even host Pink Floyd laser light rock shows by night. Use the noun planetarium for the projector that shines light onto the surface of the building's dome, recreating solar systems and constellations — and also for the building itself, where such a show is put on. Because planetarium is a Modern Latin word (from the roots planeta, or "planet," and -arium, "a place for,"), its plural can be either planetariums or planetaria.

Example Sentences

See Examples For:

planetarium planetaria planetariums

Imo Bell, a planetarium astronomer at The Royal Observatory Greenwich, says the specialist glasses are "very, very different" to regular sunglasses, which will not offer protection.

From BBC ● Aug. 11, 2026

Marshall-Lee's role at the planetarium is observing "how asteroids zip about the place, studying how they interact with each other and how they come towards the earth".

From BBC ● Apr. 1, 2026

Michelle Lopez’s video “Pandemonium” began life as a live performance inside a planetarium, and the film is a meditative look at man-made disasters.

From The Wall Street Journal ● Mar. 6, 2026

A 37-year-old convict, who had more than a year still to serve for theft, fled on November 14 during an outing with fellow prisoners to the city's planetarium.

From Barron's ● Nov. 28, 2025

It reminds me of the sixth-grade field trip to the planetarium.

From "A Mango-Shaped Space" by Wendy Mass

Eye of the Dream is an adaptation of this remarkable library of metadata, an audio-reactive Kaleidoscopic film for 360 domes and planetaria.

From The Verge ● Aug. 18, 2021

There are now six Zeiss planetaria spotted across the country.*

From Time Magazine Archive

Thus, too, the four U. S. planetaria were made possible by gifts not from practicing esthetes but from a merchant, a soapmaker, a West Coast landowner, a socialite banker.

From Time Magazine Archive

"I heard about planetaria, read about them, thought it would be well for Philadelphia to have one," he explained.

From Time Magazine Archive

Interest in planetaria is, I should say, an acquired taste; but there can be no doubt as to the industry and ingenuity of this inventor.

From A Wanderer in Holland by Herbert Marshall, R.W.S.

An alternative kind of venue is offered by Cosm, which emerged after a merger involving Evans & Sutherland, a company that developed digital projection technology widely used in planetariums and science centres.

From BBC ● Mar. 30, 2026

Cosm — a name blending cosmos and colosseums — “is a nod to our history and heritage of great scientists and planetariums and engineers,” Terry says.

From Los Angeles Times ● Sep. 26, 2023

Fairfax built state-of-the-art planetariums at eight of its high schools decades ago, an embodiment of the county’s belief that the sky was the limit.

From Washington Post ● Apr. 2, 2016

Only groups or astronomical organizations, like clubs or planetariums, that register on a website to be set up this fall will be eligible for the fun.

From New York Times ● Aug. 4, 2014

As such they were comparable to the orreries of the 18th century and to modern planetariums; that they also showed the time and rang it on bells was almost incidental to their main function.

From On the Origin of Clockwork, Perpetual Motion Devices, and the Compass by Derek J. de Solla (Derek John de Solla) Price

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