The moon doesn't actually appear larger when close to the horizon. It's an optical illusion known as the Moon Illusion.

Here's why it happens:

* Relative Size and Depth Cues: When the moon is high in the sky, there's nothing nearby to compare it to. But near the horizon, our brain sees the moon against familiar objects like trees, buildings, or the landscape. These objects act as depth cues, making the moon seem farther away and therefore larger.

* Atmospheric Distortion: The atmosphere can bend light, causing objects to appear slightly distorted, especially near the horizon. This can enhance the perceived size of the moon.

* Ebbinghaus Illusion: This is a well-known psychological phenomenon where objects appear smaller when surrounded by larger objects. The opposite happens with the moon on the horizon - the vastness of the sky makes the moon seem larger in comparison.

The truth is: The moon is the same size regardless of its position in the sky. It's our perception that's tricked by these various factors.