Gnomon A year of light

The outer ring is the horizon, the centre is the zenith, north is up. The dashed lines are the solstice paths.

The year's light

Analemma

Azimuth across, altitude up; each dot is coloured by the light at that moment. Days when the sundial runs ahead of the clock fall on one side, days when it runs behind fall on the other — that is the equation of time.