King tide occurring, predictable events. Tides are the movement of water across Earth's surface caused by the combined effects of the gravitational forces exerted by the Moon, Sun, and the rotation of Earth which manifest in the local rise and fall of sea levels. Tides are driven by the relative positions of the Earth, Sun, Moon, land formations, and relative location on Earth. In the lunar month, the highest tides occur roughly every 14 days, at the new and full moons, when the gravitational pull of the Moon and the Sun are in alignment. These highest tides in the lunar cycle are
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