Have you ever looked at the moon, as it was rising above the horizon and thought “WOW! The moon looks HUGE”, only to have it appear to shrink as it continued to rise into the night sky?
Those appearances can be deceiving, though.
The moon, while appearing to get smaller is actually staying the exact same size.
The apparent change in size is just an illusion, since the moon’s distance from the Earth does not change much in the matter of a few hours.
Part of the reason this illusion happens is because of perspective.
Your brain tries to compare the moon’s size with things around it.
In the above pictures, the moon on the right appears to be bigger because the objects surrounding it are smaller.
Without anything to compare the moons to, you can see they are the same exact size.
Another reason your brain may try to inflate the size of the moon is that it is using known comparisons.
As you look at the horizon you, and your brain, know that things appear smaller the further away they are located.
Since the moon as at the edge of the horizon, your brain is tricked into to thinking it looks bigger than when there is no horizon to compare it to.
To see this in “real life”, use something, like a coin, to compare the moon on the horizon to the moon when it is higher in the sky, and you will see that it is just an illusion!