In this picture the northern hemisphere has summer.
Based on curved light rays, the sun
can only illuminate one half of the inside world.
A satellite therefore can only photograph one half of the inside world (geocosmos).
All you have to do in this picture is to
follow the curved light rays back and then think that there is a satellite
in the place of the sun.
On the left you see the picture for spring
During the winter the path (orbit)
of the sun is inclined in such a way that the northern hemisphere receives
the least amount of light.
Just as the sun can only radiate one half of the earth due to the curved light rays, thus the satellite can only receive light from one half of the earth.
Therefore the satellite photo only shows one half of the earth as a solid convex sphere.
The paths of light are reversible. I