A planetarium is a building where lights are shone on the ceiling to represent the planets and the stars and to show how they appear to move.
planetarium in British English
(ˌplænɪˈtɛərɪəm)
nounWord forms: plural-iums or -ia (-ɪə)
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
planetarium in American English
(ˌplænəˈtɛriəm)
nounWord forms: pluralˌplaneˈtariums or ˌplaneˈtaria (ˌplænɪˈtɛriə)
1.
orrery
2.
a.
the complex revolving projector used to simulate the past, present, or future motions or positions of the sun, moon, planets, and stars on the inside of a largedome
b.
the room or building in which this is contained
Word origin
ModL < LL planeta, planet + L (sol)arium, solarium
Examples of 'planetarium' in a sentence
planetarium
Inside the planetarium, crowds of visitors watched an amazing show that recreated a night sky dense with stars.