This implies that a person unconsciously uses the horizon cues to judge the size of the moon, then he uses this perceived size of the moon to judge the relative distance of the moon. So the bigger horizon moon seems closer because it is seen as bigger. However, this explanation and the Apparent Distance Theory are not fully accepted by experts. Another more complex theory involves an explanation that describes how the eye adjusts to depth for near and far objects. This theory, scientifically called oculomotor macropsia says that the eyes are tricked into measuring the moon against nearby objects.
Experiments continue to study possible explanations on the illusion.
For now, just enjoy the moon outside and try to convince others that the moon is actually the same size at all points in the sky. Uh, needless to say, nobody believed me. Chapter 7. 5.