Tidal friction transfers angular momentum from Earth to the Moon. As a result, Earth’s rotation gradually slows, lengthening days by about 1.7 milliseconds per century. Simultaneously, the Moon drifts outward. Ancient fossils and tidal rhythmites show shorter days hundreds of millions of years ago. This relationship affects calendars and long-term climate models. It’s a delicate gravitational dance.
The effect matters for timekeeping, astronomy, and understanding Earth’s geophysical history.
It also helps model other planet-moon systems. Tidal interactions are universal in celestial mechanics.
Tidal effects from the Moon have increased day length by over 2 hours in the last 600 million years.
NASA [nasa.gov]