However, the sun is 390 times further from the Earth than is the moon. If tidal forces were based solely on comparative masses, the sun should have a tide-generating force that is 27 million times greater than that of the moon.

Based on its mass, the sun's gravitational attraction to the Earth is more than 177 times greater than that of the moon to the Earth. Our sun is 27 million times larger than our moon. The effect of distance on tidal forces is seen in the relationship between the sun, the moon, and the Earth’s waters. Gravitational attractive forces only vary inversely to the square of the distance between the objects (Thurman, H.V., 1994). Tidal generating forces vary inversely as the cube of the distance from the tide generating object.

With regard to tidal forces on the Earth, the distance between two objects usually is more critical than their masses. Tidal forces are based on the gravitational attractive force. Therefore, the greater the mass of the objects and the closer they are to each other, the greater the gravitational attraction between them (Ross, D.A. Newton’s law of universal gravitation states that the gravitational attraction between two bodies is directly proportional to their masses, and inversely proportional to the square of the distance between the bodies (Sumich, J.L., 1996 Thurman, H.V., 1994). In 1687, Sir Isaac Newton explained that ocean tides result from the gravitational attraction of the sun and moon on the oceans of the earth (Sumich, J.L., 1996). Gravity is one major force that creates tides.

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