The Lunar Effect, also known as the Moon Illusion, is an optical phenomenon in which the Moon appears larger when it is near the horizon than when it is higher in the sky. This effect is caused by the fact that when the Moon is near the horizon, it is seen in comparison to terrestrial objects such as trees and buildings, making it appear larger than when it is seen in comparison to the vastness of the night sky. The term 'Lunar Effect' is derived from the Latin word for moon, luna. The phenomenon is also related to the tides, as the gravitational pull of the Moon affects the ocean's tides.