NASA Explains Cause Behind the Moon Drifting Away From Earth

Tidal forces are causing the Moon to slowly drift away from Earth, which might have significant long-term effects, says NASA.

Highlights

• The Moon is drifting away from Earth by 4 cm per year.
• Tidal forces between Earth and the Moon are responsible for this.
• In 50 billion years, Earth and Moon may become tidally locked.

The Moon is gradually moving farther from Earth, a phenomenon explained by NASA scientists as a result of complex gravitational interactions. Currently, the Moon drifts away at a rate of approximately 4 centimetres per year, a process influenced by tidal forces between the Earth and its satellite. This steady separation, though imperceptible on a human timescale, has profound implications for the Earth-Moon system and its long-term evolution, as per the space agency.

The Role of Tidal Forces in the Moon's Drift

Earth's gravitational pull creates bulges in the Moon's shape, while the Moon's gravity exerts similar forces on Earth, most notably on its oceans. However, the tidal bulges on Earth lag slightly behind the Moon's position due to the time it takes for water to respond to gravitational changes, says NASA. This lag generates friction, slowing Earth's rotation and transferring energy to the Moon, pushing it into a higher orbit.

NASA explains that this interaction causes the Moon to drift and lengthens Earth's day by about 2 milliseconds per century. Over billions of years, this dynamic exchange of energy has significantly shaped the relationship between the two celestial bodies.

Implications for the Distant Future

If the process continues for another 50 billion years, the Moon's orbit will become so vast that Earth itself could become tidally locked to the Moon. This would mean that only one hemisphere of Earth would ever see the Moon in the sky. A similar phenomenon is already observed in the Pluto-Charon system, where the two bodies are mutually tidally locked.

While such changes occur on timescales far beyond human experience, they highlight the ongoing evolution of the Earth-Moon system, which began when the Moon formed around 4.5 billion years ago. NASA's research continues to unravel the complexities of these tidal interactions, offering insights into planetary systems within and beyond our solar system.