Perigean spring tide Perigean spring tide A proxigean spring tide (also known as a perigean spring tide) is a tide that occurs three or four times per year when the Moon's perigee (its closest point to Earth during its 29.5-day elliptical orbit) coincides with a spring tide (when the Earth, Sun and Moon are nearly aligned every two weeks). This tide usually adds only a couple of inches to normal spring tides. The Moon's orbit around Earth is elliptical, which causes the Moon to be closer to Earth and farther away at different times. The Moon and the Sun are aligned every two
Man in the Moon then cooled, becoming smooth, basalt rock. The near side of the Moon, containing these maria that make up the man, is always facing Earth. This is due to a tidal locking or synchronous orbit. Thought to have occurred because of the gravitational forces partially caused by the Moon's oblong shape, its rotation has slowed to the point where it rotates exactly once on each trip around the Earth. This causes the near side of the Moon to always turn its face toward Earth. Man in the Moon The Man in the Moon refers to any of several pareidolic images of