The moon doesn't actually get bigger, but it can *appear* bigger due to an optical illusion called the moon illusion.

Here's why it happens:

* The horizon is a reference point: When the moon is low on the horizon, our brains use the surrounding objects like trees and buildings as reference points. This makes the moon appear larger than it actually is.

* The atmosphere acts as a lens: The Earth's atmosphere bends light, making the moon appear slightly larger and distorted when it's close to the horizon.

* Psychological factors: Our brains are also prone to perceiving objects as larger when they are closer to the horizon. This is likely due to our evolutionary history, where objects on the horizon were often perceived as potentially dangerous.

So, even though the moon doesn't actually change size, our brains play tricks on us, making it look bigger when it's close to the horizon.