All information in relation to Celestial and Mercator Views are brought possible from the book:
Megalithic Science: Ancient Mathematics and Astronomy in North-West
Europe
Douglas C. Heggie
The pictures below describes the movements of the Horizon in the Mercator View.
The letters N, W, S, and E in these pictures refer to the positions,
north, west, south and east respectively.
AE is the Autumn Equinox of the sun.
WS is the Winter Solstice.
SE is the Summer Solstice.
The horizontal line in the middle is the Celestial
Equator.
The blue line is the Horizon.
The red line is the path of the Sun in
one year.
Imagine that we are standing on the celestial equator (the horizontal line in the middle). The horizon moves toward the left as shown in the pictures below. Study them carefully and notice how the horizon moves as we observe its motion from the celestial equator.
In this final picture, the horizon has moved back to its original position
in one day.