During one day, the sun describes a circle centred on the earth’s axis.
Towards us it directs a beam of parallel rays.
- Imagine just those rays which strike the tip of the pole (gnomon) and create a shadow on the ground, or on any other surface. Can the shape of the curve described in the course of a day be foreseen?
See also this figure
- For an observer with a gnomon positioned at one of the Earth’s poles, what is the shape of the curve?
- At what part of the year is the curve a straight line? Why?
