What happens to the Earth as the moon gets farther away and will it ever go away entirely? (Intermediate)

Since the moon is moving away from the earth farther and farther every year what effects will eventually start happening to the earth? Will it eventually be gone?

There is a physical principle called the conservation of momentum, which says that the Earth will have to slow down as the moon gets farther away. This means that the length of the day increases slightly - more hours in a day is probably all you wanted! However, the increased day length is a tiny tiny fraction of a second in our lifetimes.

The moon will never go away though. After billions of years (the precise number is hard to estimate), the moon will get to its final end state where it orbits more slowly and the Earth spins exactly as fast as the moon orbits. One side of the Earth will see the moon fully up in the sky while the other side of the Earth will never see the moon. This state is called tidally locked. By this time, the sun may have already become a red giant and disrupted or destroyed the Earth and moon entirely, though.

This page was last updated on July 18, 2015.

About the Author

Everett Schlawin

Everett's research focus is extra-solar planets or exoplanets. These are the planets far, far beyond Neptune and Pluto, which orbit other star systems. He observers exoplanet atmospheres to learn about their composition. The colors of an absorbing exoplanet atmosphere tell astronomers what the atmosphere is made of, so he uses spectrographs to split up the colors of these star-planet systems and infer which gases make up its atmosphere. He also is building a new infrared spectrograph to go on the Blanco Telescope in Chile with the TripleSpec 4 team.

Everett's Website: http://astro.cornell.edu/~schlawin/

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