WHY DOES THE MOON SOMETIMES APPEAR LARGER?
Reading edition
It is well known that the moon often appears larger when rising or setting—i. e., near the horizon, than when it is overhead. The same is true of the Sun. It is hardly necessary to say that these celestial bodies have not actually increased or decreased in size! Why, then, should we perceive them larger at some times than at others?
The reason for this is two-fold; psychological and optical. In the first place, the Heavens do not appear to us quite round, but somewhat flattened out, like a watch-glass. Hence the moon appears to be much further away when it rises than it does when it is overhead, with nothing between. The moon near the horizon is apparently larger because it seems further away. The second reason is that the refraction of the earth’s atmosphere gives this illusion of increased size.