A machine that computes the sky, then rebuilds it out of light.
About this scene
This is the dumbbell-shaped machine that used to stand at the centre of a planetarium dome. The perforated spheres at each end throw the stars; the cage between them carries the Sun, the Moon and the planets.
The machine holds no picture of the sky. Four axes — latitude, diurnal, annual and precession — compute when and where the sky is, mechanically. On this page those four axes are driven by real ephemeris, and the machine's posture and the sky it throws come out of one and the same calculation.
The model is not a replica of any one real instrument. It is an archetype: a machine carrying the mechanisms this whole family of projectors shares (see the Sources tab).
An archetype of this family of projectors, not a replica of a specific instrument.
Ephemeris: astronomy-engine / Geometry: procedural (no external 3D assets or textures)
Entered in UTC. The diurnal and annual axes compute this instant mechanically.
Set the latitudeThe seat view is fixed at a seated eye height, 6 m south of the dome's centre.