Gravity of Earth or (). Gravitational acceleration contributes to the total gravity acceleration, but other factors, such as the rotation of Earth, also contribute, and, therefore, affect the weight of the object. Gravity does not normally include the gravitational pull of the Moon and Sun, which are accounted for in terms of tidal effects. It is a vector (physics) quantity, whose direction coincides with a plumb bob. A non-rotating perfect sphere of uniform mass density, or whose density varies solely with distance from the centre (spherical symmetry), would produce a gravitational field of uniform magnitude at all points on its surface. The Earth
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