This phenomenon occurs due to the gravitational interaction between the Earth and the Moon, a process known as gravitational drag. The gravitational force between the two bodies causes a transfer of energy from the Earth's rotation to the Moon's orbit. As a result, the Moon slowly moves away from the Earth, while the Earth's rotation decreases much gradually.

This distancing has been observed and measured with accuracy through techniques such as observation of reflectors left on the Moon by Apollo missions and lunar probes. The process is very slow, but over billions of years, it could have a significant impact on the dynamics of the Earth-Moon system.