Moon clouds. The illuminated area of the visible sphere (degree of illumination) is given by formula_3, where formula_4 is the elongation (i.e., the angle between Moon, the observer (on Earth) and the Sun). The gravitational attraction that masses have for one another decreases inversely with the square of the distance of those masses from each other. As a result, the slightly greater attraction that the Moon has for the side of Earth closest to the Moon, as compared to the part of the Earth opposite the Moon, results in tidal forces. Tidal forces affect both the Earth's crust and oceans. The
Sun and Moon (Middle-earth) Sun and Moon (Middle-earth) The fantasy author J. R. R. Tolkien of Middle-earth fame included Earth's sun and moon for the cosmology of his myths of Arda. These astronomical bodies appear in various versions of "The Silmarillion", a history of a world, called Middle-earth populated by Elves and other fantastic creatures as well as Men. A version of "The Silmarillion", edited by the author's son and literary executor Christopher Tolkien, was posthumously published in 1977. However the Sun and Moon already appear in the author's writings dating from the 1920s. The sun and moon in Tolkien's legendarium were described in