Heard the moon is moving away from us

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In summary: The Earth's rotational energy is thus transferred to the Moon's orbital energy. Eventually the Earth will always have the same 'face' turned towards the Moon, as already the Moon's nearside 'face' is always turned towards the Earth. In summary, the Moon raises tides on the Earth, which slow the Earth down. The Moon's orbit will gain energy over time, but in the very far future it will slowly move back towards the Earth and disintegrate, leaving the Earth without a moon.
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alias25
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i heard the moon is moving away from us, does that mean its orbital speed has increased? how will that affect the rotational speed of Earth on its axis? slower?
 
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The Moon raises tides on the Earth. The Earth is rotating at a quicker rate (once per 'day') than the Moon orbits the Earth (once per 'month'). The tides in turn slow the Earth down, a phenomenon called 'tidal breaking'. As a reaction to the force raising the tides the moon 'speeds up' and slowly moves away from the Earth. I say 'speeds up' in parenthesis because as the Moon moves away from the Earth the Moon actually slows down, but it is in a higher potential energy orbit.

The Earth's rotational energy is thus transferred to the Moon's orbital energy. Eventually the Earth will always have the same 'face' turned towards the Moon, as already the Moon's nearside 'face' is always turned towards the Earth.

Garth
 
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  • #3
Garth said:
The Earth's rotational energy is thus transferred to the Moon's orbital energy. Eventually the Earth will always have the same 'face' turned towards the Moon, as already the Moon's nearside 'face' is always turned towards the Earth.

Though the moon's orbit is gaining energy and the Earth's rotation is losing it, it's worth pointing out that energy is not conserved between those two things. There is a significant amount of energy loss (in the form of heat and radiation) when the moon distorts the earth. There is not, however, another significant sink for the angular momentum, so it is fair to say that the angular momentum of the Earth's rotation is transferred to the moon's orbit.
 
  • #4
I am no expert but I am quite certain that the moon orbits the Earth eliptically which means it has a perigee and an apogee.
 
  • #5
Plastic Photon said:
I am no expert but I am quite certain that the moon orbits the Earth eliptically which means it has a perigee and an apogee.

This is true, but why do you bring it up?
 
  • #6
What happens if the Moon is moving too far from us? Could it lose the orbit, start wandering around and crash some other planet? Or even Earth?
 
  • #7
Quan Chi said:
What happens if the Moon is moving too far from us? Could it lose the orbit, start wandering around and crash some other planet? Or even Earth?
No - these orbital changes are tiny. However in the very far future the Moon will very slowly move back towards the Earth and - if it is still in existence then - the Moon will approach inside the Earth's Roche limit and disintegrate. The Earth may then end up moonless but with a beautiful set of Saturn-like rings!

Garth
 

FAQ: Heard the moon is moving away from us

1. Why is the moon moving away from us?

The moon is moving away from us at a rate of about 1.48 inches (3.78 cm) per year. This is due to the tidal forces between the Earth and the moon. As the moon's gravity pulls on the Earth, it also creates a bulge of water on the Earth's surface. This bulge creates a slight drag on the moon, causing it to gradually move away from the Earth.

2. How far has the moon moved away from us?

Since the moon was formed about 4.5 billion years ago, it has moved approximately 238,855 miles (384,400 kilometers) away from the Earth. This distance is constantly increasing by about 1.48 inches (3.78 cm) per year.

3. Will the moon eventually stop moving away from us?

Yes, eventually the moon will stop moving away from us. According to scientists, the moon will continue to move away from the Earth for about 50 billion years. After that, the Earth's rotation will have slowed down enough that the length of a day will match the length of a month. When this happens, the moon will appear to be stationary in the sky.

4. What effect does the moon moving away from us have on Earth?

The moon moving away from us has a very subtle effect on Earth. As the moon moves further away, the length of a day on Earth increases. However, this increase is so small (about 1.7 milliseconds per century) that it is not noticeable to humans.

5. Will the moon ever move closer to the Earth?

No, the moon will not move closer to the Earth. As the moon's distance from the Earth increases, the Earth's rotation slows down, causing the length of a day to increase. This process will continue until the length of a day on Earth matches the length of a month, at which point the moon will appear to be stationary in the sky.

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