planetarium

noun

plan·​e·​tar·​i·​um ˌpla-nə-ˈter-ē-əm 

plural planetariums or planetaria ˌpla-nə-ˈter-ē-ə 

1

: a model or representation of the solar system

2

a

: an optical device for projecting various celestial images and effects

b

: a building or room housing such a projector

Examples of planetarium in a Sentence

Recent Examples on the Web

Following the conversations, there was an event for children of all ages involving an indoor planetarium that spoke of the night sky and about the challenges of a flight to Mars. —Tom Teicholz, Forbes, 22 Oct. 2024

But no one should deny anyone doing a show at Sphere their chance to turn it into a planetarium. —Chris Willman, Variety, 21 Sep. 2024

An on-board planetarium offered visual journeys through the solar system, while movies played on big screens (and stateroom TVs). —Fran Golden, Travel + Leisure, 20 July 2024

For the most accurate location-specific information, consult online planetariums like Stellarium and The Sky Live. —Jamie Carter, Forbes, 30 Sep. 2024

Word History

First Known Use

1860, in the meaning defined at sense 1

Kids Definition

planetarium

noun

plan·​e·​tar·​i·​um ˌplan-ə-ˈter-ē-əm 

plural planetariums or planetaria -ē-ə 

1

: a device that projects images of heavenly bodies on a ceiling shaped like a dome

2

: a building or room housing a planetarium