The answer is refraction, or the bending of light,
it's more easily observed here on earth because of the atmosphere.
It's the same reason that the moon 'changes' sizes as it rises and falls.
Since we generally only photograph from the light side of the moon,
the earth is not often seen near the horizon of the moon,
and is only seen when it is in it's 'shrunken' form.
There's my answer to a 4yr-old question no one cared about answering