secular acceleration of the Moon
astronomy
Quick Summary
Secular acceleration of the Moon refers to the gradual, consistent change in its orbital speed and distance from Earth. This phenomenon is primarily caused by tidal friction.1
Here's a breakdown:
- Tidal Bulge: The Moon's gravitational pull creates a bulge in Earth's oceans and crust. Earth's rotation carries this bulge slightly ahead of the direct line between Earth and the Moon.
- Gravitational Interaction: The Moon's gravity then pulls on this leading bulge. This pull acts as a slight acceleration, causing the Moon to gradually move farther away from Earth by about 3 centimeters per year.1
- Effect on Earth: Conversely, this interaction slows down Earth's rotation, lengthening our day by a tiny fraction of a second each year.1
This process is a key aspect of celestial mechanics and is responsible for the Moon's synchronous rotation, where it always shows the same face to Earth.2
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