AST101H1 Lecture Notes - Lecture 5: Tidal Locking, The Moons

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST101H1
• Professor: Bryan Gaensler

Document Summary

The force of gravity depends on the distance. The point of the earth closest to the moon experiences the most force. The point on the earth furthest experiences the least force. So: the furthest is pulled on by the middle which is pulled on by the closest. So: the earth is stretched in line with the moon. One is facing the moon, and one is on the opposite side. Tides are not aligned perfectly with the moon because earth rotates. The slight bulge causes the earth"s rotation to (slightly) slow down. Tidal forces from the earth on the moon are larger. The moon"s rotation has slowed down until it is tidally locked. If the earth didn"t rotate, tidal bulges would be oriented along the earth-moon line. Friction with the rotating earth pulls the tidal bulges slightly ahead of the earth-moon line. The moons gravity tries to pull the bulges back into line, slowing earth"s rotation.