Earth tide Earth tide Earth tide (also known as solid Earth tide, crustal tide, body tide, bodily tide or land tide) is the displacement of the solid earth's surface caused by the gravity of the Moon and Sun. Its main component has meter-level amplitude at periods of about 12 hours and longer. The largest body tide constituents are semi-diurnal, but there are also significant diurnal, semi-annual, and fortnightly contributions. Though the gravitational forcing causing earth tides and ocean tides is the same, the responses are quite different. The larger of the periodic gravitational forces is from the Moon but that of the
Full moon full moons rise around the time of sunset. Because the moon moves eastward among the stars faster than the sun its meridian passage is delayed, causing it to rise later each day – on average by about 50.47 minutes. The harvest moon and hunter's moon are unique because the time difference between moonrises on successive evenings is much shorter than average. The moon rises approximately 30 minutes later from one night to the next, as seen from about 40 degrees N or S latitude. (This is because a full moon in September appears to move not straight east but north-east