Moon on the Horizon Appears Bigger: The Brain's Size Trick
The Moon looks larger near the horizon due to the Moon Illusion, a brain-based effect in which our perception of distance and size is distorted by contextual cues (like trees, buildings, or a flat horizon). Refraction actually makes the Moon look squished, not bigger, so the size increase is not atmospheric. The leading explanation involves Emmert's Law: the retina records the Moon’s size, but we judge its distance and thus its apparent size based on context, a two-step process that makes horizon objects appear larger even though nothing about the Moon’s actual distance changes.