Earth is not an object like a point (· ), but a rigid body (●) with a certain volume, so the gravity applied to each part is slightly different. This difference in gravity applies to all celestial bodies of volume. In the case of the Earth, only seawater is attracted, but in the case of a satellite orbiting a large planet, it cannot withstand this force and the satellite itself is destroyed.
The reason why the same tidal power occurs on the front and back of the moon
There are two main types of forces on the Earth's seawater.
- Gravity of the Moon: The lunar gravitational force, which is not parallel according to latitude, but inclined little by little toward the moon.
- Centrifugal force: This is the inertial force generated by rotating motion around the EMB (Earth-Moon Common Mass).
By vector synthesis of the above two forces, you can find out the magnitude and direction of the tidal force acting on the Earth.