Why Does the Moon Look Larger Near the Horizon?

Perhaps you saw the total lunar eclipse last night, or maybe it was only umbral (partial) in your area. Either way, it reminds us of God’s intricate design that allows advanced life on this planet. As you watched the Moon, you may have seen it close to the horizon or high in the sky. Why does the Moon look larger near the horizon? Is it really larger, or are your senses being fooled?

Here is a simple experiment you can do with a camera or smartphone. Take a picture of the Moon when it rises and then take another picture of it high in the sky on the same night. Now compare the Moon’s size in the two pictures. You will see that the Moon is the same size. Better yet, stretch out your arm and compare the Moon’s size to your thumb at the two positions on the same night.

If you are thinking that the Moon looks larger at the horizon because it is farther away at that time, that is clearly not the case. The Moon’s distance, and therefore apparent size, does vary somewhat throughout the year, but not on the same night. The difference in apparent size when the Moon is closest to Earth and farthest away is only about 7%. The human eye can barely detect that difference.

So why does the Moon look larger near the horizon? First, realize that it is not our eyes but the human brain that does the seeing. When the Moon is near the horizon, we compare it to distant trees and buildings that we know are large, so we think the Moon looks larger. However, when it is in the middle of the vast, open sky, the Moon seems small by comparison.

We interpret what we see based on previous experiences and prejudices. That means our brain interprets new information filtered through those prejudices. That brings up another question. How does the human mind interpret other areas of understanding, such as the existence of God? Are there filters in your line of sight that can block you from seeing the truth?

— John N. Clayton © 2022

Reference: Discover Magazine