moon: Tidal Influence of the Moon

The gravitational influence of the moon is chiefly responsible for the tides of the earth's oceans, the twice-daily rise and fall of sea level. The ocean tides are caused by the flow of water toward the two points on the earth's surface that are instantaneously directly beneath the moon and directly opposite the moon. Because of frictional drag, the earth's rotation carries the two tidal bulges slightly forward of the line connecting earth and moon. The resulting torque slows the earth's rotation while increasing the moon's orbital velocity. As a result, the day is getting longer and the moon is moving farther away from the earth. The moon also raises much smaller tides in the solid crust of the earth, deforming its shape. The tidal influence of the earth on the moon was responsible for making the moon's periods of rotation and revolution equal, so that the same side of the moon always faces earth.

Sections in this article:

• Introduction
• Formation and Evolution
• Internal Structure
• Surface Features
• Physical Characteristics
• Tidal Influence of the Moon
• Solar and Lunar Eclipses
• Retarded Lunar Motion
• The Lunar Orbit and Phases
• The Lunar Month
• The Earth-Moon System
• Bibliography

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