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

The parade will start June 3, when Mercury, Mars, Jupiter, Saturn, Uranus and Neptune will be aligned, according to Star Walk Astronomical News, a planetarium phone app. —Tribune News Service, The Mercury News, 27 May 2024

The telescope’s image also was broadcast into the Science Center’s indoor planetarium, where staff members showed a NASA livestream from the eclipse’s path across the United States, from Texas, across the Midwest and through northern New England. —Christine Condon, Baltimore Sun, 8 Apr. 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