Celestial globes display the apparent positions of the stars in the sky. They omit the Sun, Moon, and planets because the positions of these bodies vary relative to those of the stars, however the ecliptic, or path of the sun across the sky, is marked.
An interesting design issue for a celestial globe concerns “handedness”. Suppose the globe is constructed so that the stars are in the positions they occupy on the imaginary celestial sphere. In that case, the star field is represented as reversed on the surface of the globe (all constellations appear as mirror images).
This is because the view from Earth, at the centre of the celestial sphere, is a gnomonic projection inside of the celestial sphere, whereas the celestial globe is an orthographic projection viewed from the outside. As a result, celestial globes are often produced in mirror image, so that the constellations appear, and are recognisable, as viewed from Earth (gnomonic projection). This ambiguity is seen in the astronomical ceiling of New York City’s Grand Central Terminal, whose inconsistency was left uncorrected; although it was noticed soon after the terminal opened in 1913, because a commuter noticed the zodiac was backward.
Our discussion highlights the clarity that perspective theory/methods bring to the spatial science(s); or of how we view/perceive, image, map, measure, calculate, and represent/model, the physical world around us.
Perspective Research Centre 
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