Earth referred to as "moons", after Earth's. The gravitational attraction between Earth and the Moon causes tides on Earth. The same effect on the Moon has led to its tidal locking: its rotation period is the same as the time it takes to orbit Earth. As a result, it always presents the same face to the planet. As the Moon orbits Earth, different parts of its face are illuminated by the Sun, leading to the lunar phases; the dark part of the face is separated from the light part by the solar terminator. Due to their tidal interaction, the Moon recedes
Chinese sun and moon mirrors "fangzhu" mirrors "jiàn" 見 "seeing" the sun and moon. The Way of Heaven is called the Round; the Way of Earth is called the Square. The square governs the obscure; the circular governs the bright. The bright emits "qi", and for this reason fire is the external brilliance of the sun. The obscure sucks in "qi", and for this reason water is the internal luminosity of the moon. Emitted "qi" endows; retained "qi" transforms. Thus yang endows and yin transforms. The unbalanced "qi" of Heaven and Earth, becoming perturbed, causes wind; the harmonious "qi" of Heaven and Earth, becoming calm,