Abstract

The Earth’s diametrically opposed, presumably symmetric, tides are due to the Moon’s differential gravitational force varying across the Earth. This is not intuitively obvious, but becomes clear when the physics is examined mathematically. The presumed symmetry is due to an approximation that holds when the radius of the affected body (e.g., the Earth) is much less than its center-to-center distance from the affecting body (e.g., the Moon). The exact solution indicates an asymmetry, which becomes more pronounced as the assumption loses its applicability.