Orbit of the Moon attraction that the Moon exerts on Earth is the cause of tides in the sea; the Sun has a smaller tidal influence. If Earth had a global ocean of uniform depth, the Moon would act to deform both the solid Earth (by a small amount) and the ocean in the shape of an ellipsoid with the high points roughly beneath the Moon and on the opposite side of Earth. However, because of the presence of the continents, Earth's much faster rotation and varying ocean depths, this simplistic visualisation does not happen. Although the tidal flow period is generally synchronized to
Gravitation of the Moon spacecraft acceleration can be measured by small shifts in frequency of the radio signal, and the measurement of the distance from the spacecraft to a station on Earth. Since the gravitational field of the Moon affects the orbit of a spacecraft, one can use these tracking data to detect gravity anomalies. However, because of the Moon's synchronous rotation it is not possible to track spacecraft from Earth much beyond the limbs of the Moon, so until the recent GRAIL mission the far-side gravity field was not accurately known. A major feature of the Moon's gravitational field is the presence of