planetarium has definitions from the fields of physics,astronomy,optics
1
[ noun ] (physics,astronomy,optics) an optical device for projecting images of celestial bodies and other astronomical phenomena onto the inner surface of a hemispherical dome

Related terms

optical_device

2
[ noun ] (astronomy) a building housing an instrument for projecting the positions of the planets onto a domed ceiling

Related terms

building

3
[ noun ] an apparatus or model for representing the solar systems

Related terms

model model orrery

*