# How long will it take for the Earth to become tidally locked to the Moon?

• mofobro
In summary, according to an article, the Earth will eventually become tidally locked to the moon, with one face always facing the moon, due to a process called tidal braking. However, the exact timeframe for this process is uncertain, as the rate of tidal braking is not constant and will be affected by factors such as the moon's recession from the Earth and the eventual loss of Earth's oceans. A rough estimate suggests that the Earth's day could become 60 hours long in about 5 billion years, but this may not be accurate due to other factors. Ultimately, the process of becoming tidally locked could take an extremely long time, possibly even longer than the lifespan of our sun.

#### mofobro

According to an article I read,

the Earth will one day become tidally locked to the moon the way the moon is locked to the Earth today, so that the same face of the Earth always faces the moon.

If this is true, how long will that process take?

Tidal braking is slowing the Earth's rotation by about a millisecond per century. Assuming that was to remain constant, it would take so long for Earth to become tidally locked with the moon, our sun would have long since become a white dwarf. We do, however, know the assumption of constant braking is invalid. Tidal braking also causes the moon to receed from Earth which will diminish the braking effect over time. We also know that Earth will lose its oceans within a few billion years, which will eliminate the source of most tidal braking. In short, the answer effectively becomes nearly eternity.

A slightly better rule-of-thumb is that the Earth loses a third of its rotational energy per billion years. Over 5 billion years, that yields a factor of (2/3)^5 ~ 32/243 ~ 1/7.5 and hence a factor of between 2.5 and 3 for the rotational period (inverse square dependence on energy). So, if things were to continue going smoothly, the day would be some 60 hours long by the end. However, as Chronos said, the oceans are expected to evaporate long before that, which will make further braking far less effective.

## 1. How long will it take for the Earth to become tidally locked to the Moon?

The process of tidal locking, where a celestial body's rotation becomes synchronized with its orbit, is a gradual one and can take millions of years. In the case of the Earth and Moon, it is estimated that it will take about 50 billion years for the Earth to become fully tidally locked to the Moon.

## 2. What factors influence the speed at which the Earth becomes tidally locked to the Moon?

The main factor that influences the speed of tidal locking is the distance between the two bodies. The closer the two bodies are, the faster the process will occur. Other factors, such as the size and composition of the bodies, can also play a role.

## 3. Will the Earth ever become completely stationary in relation to the Moon?

No, the Earth will never become completely stationary in relation to the Moon. Tidal locking only results in one side of a body always facing the other, not complete stillness. The Earth will continue to rotate, but at a rate that is synchronized with its orbit around the Moon.

## 4. Can the Earth's rotation be affected by other celestial bodies?

Yes, the Earth's rotation can be affected by other celestial bodies. The gravitational pull of other planets and the Sun can cause slight variations in the Earth's rotation, but these effects are minimal compared to the strong tidal forces exerted by the Moon.

## 5. How does the Earth being tidally locked to the Moon affect our planet?

The Earth being tidally locked to the Moon has several effects on our planet. It leads to the creation of tides, as the Moon's gravity pulls on the Earth's oceans. It also stabilizes the Earth's axial tilt, which is responsible for our seasons. Additionally, it can impact the length of our day, as the Earth's rotation slows down due to the tidal forces from the Moon.