LUNAR TIDES ARE LARGER THAN SOLAR TIDES FREE

Where Earth ’s surface is at any angle other than 90 ° to the line connecting the center of Earth to the center of the moon, water experiences a horizontal component of this centrifugal force. This centrifugal force has the same magnitude and direction at every point on and in Earth (i.e., away from the moon parallel to a line connecting the center of Earth to the center of the moon). As Earth and moon revolve around this point like dancers spinning with linked hands, all points on both bodies experience a centrifugal force. In the case of the Earth-moon system, the common center of mass happens to be inside Earth, about 1,068 miles (663 km) beneath the surface along a line connecting the center of Earth to the center of the moon. This second bulge forms as follows (focusing on the ocean tide alone, for clarity): the moon and Earth, like all pairs of bodies orbiting each other in space, actually orbit around their common center of mass (that is, the point where, if their individual centers were attached to opposite ends of a rigid stick, the stick could be suspended from a string and remain in balance).

LUNAR TIDES ARE LARGER THAN SOLAR TIDES FREE

Since water is free to move horizontally, the oceans tend to flow over Earth ’s surface and collect in a secondary bulge on top of the Earth tide this water bulge is termed an ocean tide.Īt the same time, an Earth tide and an ocean tide form on the opposite side of Earth, directly away from the moon. This force causes Earth itself to bulge slightly toward the moon. The side of Earth that faces the moon experiences a larger gravitational pull, due to the moon ’s closer proximity, than other parts of Earth. English physicist Sir Isaac Newton (1642 –1727) first succeeded in mathematically describing the tides in what is known as the equilibrium tidal theory. This explanation is now known to be basically correct, although it was not widely accepted by scientists until the eighteenth century. (Tides were essentially absent from the Mediterranean Sea, which was more familiar to the Greeks.) Pytheas proposed an explanation for tidal action: the pull of the moon on Earth ’s oceans, he said, caused the tides. In about the third century BC, Pytheas traveled outside the Straits of Gibraltar and observed tidal action in the Atlantic Ocean. One of the earliest careful observers of ocean tides was the Greek geographer Pytheas of Massalia. As far as Earth is concerned, the most important tidal phenomena are the ocean and ground tides that occur as a result of the moon ’s and the sun ’s gravity. All bodies in the universe exert tidal forces on each other, although the effects are generally too small to observe. Tides are deformations in the shape of a body caused by the gravitational force of one or more other bodies.

Effect of the moon ’s motion around Earth

Lunar tides are larger than solar tides