NASA has shed light on the phenomenon of the Moon's gradual separation from Earth, revealing that tidal forces are at the heart of this cosmic drift.
The Moon is currently moving away at a rate of about 4 centimeters per year, a process that, while slow on a human scale, has significant implications for the future of the Earth-Moon system.
Gravitational interactions between the Earth and the Moon are responsible for the separation. The Earth's gravity creates tidal bulges on the Moon, and the Moon exerts similar forces on Earth's oceans. However, Earth's tidal bulges lag slightly behind the Moon's position due to the time it takes for water to respond to gravitational shifts.
This delay generates friction, gradually slowing Earth's rotation and transferring energy to the Moon. As a result, the Moon is pushed into a higher orbit, and Earth's day lengthens by about 2 milliseconds per century, according to NASA. This dynamic has been shaping the relationship between the two celestial bodies for billions of years.
If this drift continues unchecked for another 50 billion years, the Moon’s orbit could expand to the point where Earth itself becomes tidally locked to the Moon. In such a scenario, only one side of the Earth would ever face the Moon, mirroring the mutual tidal locking seen in the Pluto-Charon system.
Though these changes occur on an almost incomprehensible timescale, they underscore the ongoing evolution of the Earth-Moon system. The relationship began around 4.5 billion years ago when the Moon first formed and has continued to evolve through these complex gravitational interactions.