Why does the moon look bigger near the horizon?(달에 대한 착시현상)

<written in 2019.2.7>

In 2017, when I was on a trip with my family, I noticed that the moon looked way much bigger than it usually was. I wondered why and decided to research more about the phenomenon when I got home. 

           the moon looks bigger than usual in the picture                (photo taken by me, at Anaheim)

There is no proven reason to why the moon looks bigger near the horizon. However, one thing is for sure: that it has something to do with our brain's functions. The current most widely accepted theory is that the phenomenon is caused by people's sense of distance. Normally, this 'skill' is a great advantage for survival and to identify objects and measure distances quite correctly. But in some situations, the brain can be tricked into showing us optical illusions. This may also be the case for the 'big moon'. Compared to buildings near the horizon, the moon might look similar in size(at first). But since we know that the moon is farther away from us than the buildings are, our brain thinks it should actually be larger in size, therefore leading to an optical illusion where the moon looks bigger than it should be seen as.

https://www.college-optometrists.org/

For example, look at this illustration above. The size of the girls are acually the same, but most people will see it as getting bigger to the back. This is because the background makes the brain to believe that the girl in the right is farther away than the girl in the left. Our brain knows by experience that faraway objects seem smaller than when it is nearer. Therefore, the brain concludes that the girl in the right should be the biggest. This is how a sense-of-distance-based optical illusions occur.

another example of distance-related illusions