Do you know what produces the tides?

Do you know what produces the tides?

Three stars influence the tides: The Moon, The Sun and The Earth. Of the three, the moon is the most influential. High tides are repeated approximately every twelve hours. Curiously, because of these gravitational forces the two highest tides occur on diametrically opposite sides and in more or less a direct line with the moon.

The high tide, therefore, repeats every 12 hours and 25 minutes, anywhere on the planet. That time is half of that used by the moon to return to approximately the same position (in orbiting the Earth). This is because the Moon exerts a pulling force on the ocean water that is on the side of the Moon, pulling on the water of the Earth, but it also exerts a force on the Earth pulling away the water on the opposite side. Thus, the two tides occur on the diametrically opposite sides and in line with the position of the Moon. Actually, it is not exactly in line with the Moon, since the water moves more slowly following the speed of the Moon, but with a delay.

As a side effect this makes the rotation of the earth slow down so that the days get longer (about 2 thousandths per century). In addition the Moon accelerates and consequently moves away from Earth (about 3 cm per year). The Sun also produces tides, but these are about one-third smaller than those produced by the Moon. Thus, during the New Moon and Full Moon (2 times a month) these forces are aligned to obtain larger tides than normal (spring tides or syzygy). During the lunar quarter, the fourth crescent and waning (also twice a month), the two forces are decompensated causing smaller tides than usual (dead low tides or quadrature).

The Sun, therefore, also exerts its force of gravity. Although to a lesser extent, it contributes to the tides twice a month during the cycles of full moon and new moon, combining its forces and producing tides that are lower and higher than usual.

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