Is the moon being pulled towards earth, or flying away from us?

Question

I heard that the moon is slowly but steadily pulling earth towards it, and im arguing with my friend, who thinks the earth is being pulled into outer space slowly. We both know that it is not going to be immediate, I know. But Im looking online for the answer, and I find mixed results, not finding a definate answer. Which is it?

I forgot to ask, but PLEASE show sources :(

Answer 1

Most of the answers so far are very imaginitive, but wrong.

The moon is being pulled toward the earth, (and vice-versa, according to Newton's 3rd Law); AND it is gradually moving away from us.

Gravity is always an attractive force, and every massive body attracts every other massive body. Think of gravity as a rubber band which is pulling the earth and moon toward each other with a strength of about 44 billion billion pounds of force.

However, just because something is being pulled toward you doesn't mean it gets closer. Think of attaching a ball to a long rubber band and then swinging it around your head. There is tension in the rubber band, which means there is definitely a force pulling the ball toward the center; however, the ball's sideways momentum prevents it from actually snapping inward toward your hand. The same sort of thing happens with the moon as it orbits the earth.

The moon's average distance is about 239,000 miles. However, the moon doesn't move in a perfect circle; over the course of a month, the moon's distance from the earth varies, moving alternately in and out by a distance of about 26,000 miles(!) This is 13 times the moon's diameter.

Superimposed on top of that monthly back-and-forth motion, is an extremely tiny drift -- only about an inch per year -- away from the earth. So the _average_ distance to the moon is very slowly increasing. But at any _given_ moment, the moon may be moving either closer to or farther from the earth, just because its orbit is not a perfect circle.

As far as "...the earth being pulled into outer space...", I'm not sure what that means, since the earth is _already_ in outer space(!) Does your friend mean, the earth is being pulled away from its orbit around the sun? If so, please assure him that this is not the case.

Answer 2

You're both wrong. The moon is not pulling the Earth anywhere, and the Earth is not being pulled into outer space.

The moon's gravity causes tides on the Earth, and those tides cause friction between the ocean and the seafloor. And this friction is very gradually slowing the Earth's rotation (by a few seconds a century).

The law of conservation of momentum states that the total momentum of a system (the rotation of the Earth and the moon and the orbits of the 2 objects around the centre of gravity) has to remain the same. So if the Earth is slowing down, then something has to change to conserve momentum.
That could be the moon speeding up (which it can't do) or the moon moving further from the Earth (which it can do, and is doing).

The Earth/Moon system is held in orbit by the sun's gravity, and the only way the Earth could be pulled into outer space was by another large object's gravity (and there is no large object anywhere near by to pull the Earth anywhere).
The moon certainly doesn't have the mass or gravity to pull the Earth anywhere (its the Earth that keeps the moon in orbit).

Answer 3

The moon is actually flying away from the Earth ever so slowly. Earth's rotational momentum is being transferred into the Moon, which increases its energy, which makes it orbit farther from Earth. Consequently, the Earth's rotation is slowing down by the same process.

In the end, the Earth will rotate with the same period that the Moon orbits it. This is called tidal locking. The Earth has already done this to the Moon, since the Moon has so much less mass than the Earth does.

The reason is this: The Moon's gravity slightly squashes the Earth. This is where tides come from. This slightly squashed shape causes the effect of gravity to be slightly stronger at some points than others, which puts a bit of torque on the Earth. Since for every action, there's an equal and opposite reaction; since the leading bulge of the Earth is being pulled back towards the Moon, the Moon is in turn being pulled towards that bulge. This is how the momentum is being transferred... somewhat similar to gravity boosts like space probes use when flying by Jupiter on their way out to Saturn and beyond.

Answer 4

The moon cannot pull the earth towards it due to the moon being so comparitivly light, and having less gravitational pull than the earth. Everything in the universe is moving outwards, including the earth, so if you want to put it in such terms the earth is being "pulled into outer space". This has been shown by red shift. The moon is in the earth's orbit, we are not going to get pulled into the moon and have some head-on collision. And if we did...earth could take the moon any day(!)

Answer 5

The near approach of an asteroid that had the mass to drive the moon into the sun would also have a catastrophic effect upon the earth's orbit as well. In addition, I believe that the moon would be much more likely to shatter than to absorb the impact and depart in one piece, and the earth's gravitational attraction could well bring sizable moon chunks into collision with us, another catastrophe!! It is not true that the moon revolves around the earth. Rather, both bodies revolve around our common center of gravity. I suspect that the disappearance of the moon would move the center of that orbit to the center of the earth with a corresponding increase in the earth's rotation rate to conserve angular momentum. Let's pray it doesn't happen!!

Answer 6

I saw a program on the Discovery Channel called "If We Had No Moon". It was narrated by Patrick Stewart. It was stated in the program that the moon was slowly moving away from us at about 1 inch per year.

Answer 7

The moon is slowly moving away from the earth.

Answer 8

The moon is pulling away about an inch every 100 years. And it will continue that way until it finally breaks free. But that won't take place for several hundred million years.

Answer 9

You two really need to get a science textbook! The gravity force of the larger object holds the smaller object in orbit around it. The gravity force of the Sun holds the earth and remaining planets around it. Some of the planets, including earth hold moons orbiting around them.

Answer 10

Hi. The Moon gains angular momentum due to tidal forces and is moving away. I'll find a source... Here you go. http://www.astronomynotes.com/gravappl/s10.htm