Armillary Sphere

An armillary sphere is a model of the celestrial sphere. The drawing is from Christoph Clavius commentary on the book De Sphaera from 1581.

This grasshopper definition generates the position of ecliptic and sun for a given time, timezone and date at a given position on earth. The real position of the sun deviates from this position by approx. +/- 15 min. The reason is the eccentricity of the earths's orbit around the sun. (see equation of time).

Download the grasshopper definition here