Why the Moon Appears Larger at the Horizon

An astronomer observed the moon rising, noting its enormous appearance against the horizon. Despite knowing the moon's actual size remains constant, the visual perception changes based on the moon's position in the sky. Observations show that the moon looks larger when near the horizon due to misinterpretation of distance by the human brain. This phenomenon, known as the moon illusion, derives from a combination of the Ponzo illusion and our perception of spatial relationships. The brain perceives the moon as being farther away on the horizon, leading to the belief that it must be larger. This illusion persists even in empty horizons, indicating that other explanations, such as comparison with nearby objects, are insufficient for understanding this visual trick. Thus, the astronomical phenomenon highlights the complexities of human visual perception and cognition.