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
Counter-Earth its planets—at the center of the solar system because of the gravitational pull of the most massive planet—Jupiter. The Sun wobbles around the "true" center known as a barycenter, which lies just inside the Sun. When the Sun's position is 90 degree from the barycenter relative to Earth, it would come close to "unblocking" from view a planet 180 degrees from Earth, enough to reveal the aforementioned hypothetical signature. For a Counter-Earth orbiting the same path as Earth to always stay 180 degrees from Earth, the two planets would have to have circular orbits, but Earth's orbit is elliptical. According