The Moon Is Slowly Drifting Away from Earth

This cosmic separation is a result of the intricate gravitational dance between our planet and its satellite. The Moon’s gravity pulls on Earth’s oceans, creating tidal bulges. Because Earth rotates faster than the Moon orbits, these bulges of water are dragged slightly ahead of the Moon. This leading mass of water exerts a gravitational tug on the Moon, pulling it forward and boosting it into a higher orbit, thus causing it to drift farther away. This process is a two-way street; as energy is transferred to the Moon to speed it up, it is taken from the Earth's rotation, causing our planet's spin to slow down.

The consequences of this exchange are profound over geological timescales. Evidence from 70-million-year-old fossil shells shows that a day on Earth was once only 23.5 hours long. As the Moon continues its slow retreat, our days will continue to lengthen, albeit by only a few milliseconds per century. While ancient Greek astronomers like Aristarchus made early estimates of the lunar distance using eclipses, modern science provides a much clearer picture. The laser reflectors placed on the Moon allow for incredibly precise measurements, confirming this gradual recession with millimeter accuracy.

Looking into the far future, this process would eventually cause Earth's rotation to slow so much that it would become tidally locked with the Moon, with one side of our planet perpetually facing it. However, this is a scenario for the very distant future, billions of years from now. Long before that happens, the Sun is expected to evolve into a red giant, which will likely disrupt or destroy the Earth-Moon system.