The Moon Slowly Lengthens Earth's Day

The Moon’s gravity raises tides, and tidal friction transfers some of Earth’s rotational energy to the Moon’s orbit. Over the long term, this slows Earth’s rotation and lengthens the day. The changes are not uniform: the atmosphere, oceans, interior mass movement, and water redistribution can temporarily speed up or slow down the rotation. Geological records show that days were shorter in the distant past.