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vincentm
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What would be the effects of Earth not having a moon? I know that our moon is slowly drifting away. But what would happen then?
There have been arguments that, without our moon, life on Earth would not be possible, but I think that's a little over the top myself.
Ophiolite said:A substantial part of the reduction in day length is a consequence of the tidal interaction of the Earth and the moon.
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It didn't in the original H.G. Wells book, it was only the 2002 Time Machine movie where the moon blew up...the explanation they gave there was that people were using nuclear bombs as part of mining operations on the moon.EnumaElish said:I forgot what made the moon fall to Earth in H.G. Wells' Time Machine.
According to this, it's drifting away at about 4 cm per year, and billions of years in the future it will stop drifting away when the length of the Earth's day is the same as the length of the moon's orbit (around 47 modern days), at which point the moon will be about 1.35 times as far away as it is now.marcus said:I don't think the moon is drifting away fast enough to worry about,
does anyone remember an estimate about that?
Oh, I hope life will not imitate art in this case!JesseM said:It didn't in the original H.G. Wells book, it was only the 2002 Time Machine movie where the moon blew up...the explanation they gave there was that people were using nuclear bombs as part of mining operations on the moon.
And what is the reason for the day stretching to 47 times its current length?JesseM said:According to this, it's drifting away at about 4 cm per year, and billions of years in the future it will stop drifting away when the length of the Earth's day is the same as the length of the moon's orbit (around 47 modern days), at which point the moon will be about 1.35 times as far away as it is now.
According to the page, the drifting away of the moon is related to the slowing of the rotation of the Earth because of "tidal friction", which transfers the Earth's rotational momentum to the moon's orbital momentum. http://curious.astro.cornell.edu/question.php?number=124 gives a slightly more detailed explanation of how tidal friction works:EnumaElish said:And what is the reason for the day stretching to 47 times its current length?
The reason for the increase is that the Moon raises tides on the Earth. Because the side of the Earth that faces the Moon is closer, it feels a stronger pull of gravity than the center of the Earth. Similarly, the part of the Earth facing away from the Moon feels less gravity than the center of the Earth. This effect stretches the Earth a bit, making it a little bit oblong. We call the parts that stick out "tidal bulges." The actual solid body of the Earth is distorted a few centimeters, but the most noticable effect is the tides raised on the ocean.
Now, all mass exerts a gravitational force, and the tidal bulges on the Earth exert a gravitational pull on the Moon. Because the Earth rotates faster (once every 24 hours) than the Moon orbits (once every 27.3 days) the bulge tries to "speed up" the Moon, and pull it ahead in its orbit. The Moon is also pulling back on the tidal bulge of the Earth, slowing the Earth's rotation. Tidal friction, caused by the movement of the tidal bulge around the Earth, takes energy out of the Earth and puts it into the Moon's orbit, making the Moon's orbit bigger (but, a bit pardoxically, the Moon actually moves slower!).
The Earth's rotation is slowing down because of this. One hundred years from now, the day will be 2 milliseconds longer than it is now.
JesseM said:According to http://www.physlink.com/Education/AskExperts/ae429.cfm , it's drifting away at about 4 cm per year, and billions of years in the future it will stop drifting away when the length of the Earth's day is the same as the length of the moon's orbit (around 47 modern days), at which point the moon will be about 1.35 times as far away as it is now.
Without the moon's gravitational pull, the tides on Earth would be significantly reduced. The tides are primarily caused by the moon's gravity, so without it, the tides would be about one-third of their current size.
The moon plays a crucial role in stabilizing Earth's tilt, which is responsible for our seasons. Without the moon, Earth's tilt would vary greatly, leading to extreme and unpredictable climate changes.
Yes, without the moon's gravitational pull, Earth's rotation would slow down significantly. This would result in longer days and nights, making our concept of time and seasons very different.
It is difficult to say for certain, but it is likely that the lack of a moon would have a significant impact on life on Earth. The moon has played a crucial role in the evolution of life on our planet, and its absence could have a ripple effect on ecosystems and species.
The moon has been a crucial target and stepping stone for space exploration, so without it, the course of human space exploration would have been very different. Additionally, without the moon's gravity, it would be much more difficult to launch spacecraft from Earth.