1.a building housing an instrument for projecting the positions of the planets onto a domed ceiling
2.an optical device for projecting images of celestial bodies and other astronomical phenomena onto the inner surface of a hemispherical dome
3.an apparatus or model for representing the solar systems
Idiom of the Day
from way back
since a long time ago, for a long time
I know my friend from way back. In fact, we went to elementary school together.