How does the moon affect our tides at such a distance away?

Question

From this scale it looks too far away to have an effect http://upload.wikimedia.org/wikipedia/commons/6/6a/Earth_to_moon_vertical1.png

Answer 1

gravity

Answer 2

The tides are caused by gravity literally pulling the ocean towards the moon as it passes over the water.

Gravity is a relativley week energy compared to electromagnetic sources, but it is still quite potent. Look at the distance that the earth is from the sun. That is a gigantic distance and yet it is still powerful enough to keep the earth in orbit.

Even the planets are thought to have an effect. Einstien subscribed to one theory that stated that the earths crust sat on a lava pool, like a loose orange peel and that by alligning all of the planets the gravitational forces would be enough to pull the weighty ice caps towards the centre of the earth, dragging the crust with them (Nice biblical disaster theory).

I don't know how valid the above is, but the point is that even our great scientists believe that gravitational forces can have an effect over great distances.

For further study you might want to look into something called a gravity well. For now, consider that you have a piece of lycra stretched over a frame. You have placed a metal ball in the middle, causing the material to sag. Now place a ball bearing at the edge and shoot it towards the other side. You will see that the ball bearing becomes effected by the sagging material. This should give you an idea of how gravity can have an effect over distances.

Hope this helps.

Answer 3

The attraction between objects is small at a distance, but massive objects, like the earth and moon, start with a great deal of mass. So the moon and sun are both pulling on thhe earth, enough for the earth and moon to continue to orbit the sun and earth respectively.

The force between the earth and the moon can be worked out using the equation F=Gmm/r^2 where G is the gravitational constant (6.67300 × 10^-11 m3 kg^-1 s^-2) and the two 'm's are the mass of the earth and moon and r is the distance between. The earth weighs 5.98 × 10^24, the moon weighs 7.35x10^28kg and the distance between them is 3.84 x10^8m so (if I pushed the right buttons) that means the force between the earth and moon is near enough 2x10^26 Newtons or 2x10^25 kg (we really don't need all those decimal places for this discussion) or 2x10^22 tons.

So although the distance is great the masses are greater so we have significan, massive, gravitational attraction. After all it has to turn the moon 360 degrees every 27 days or so.

Without the moon we'd still have tides, but they'd always be the same. The moon adds variation. When the moon is full it is at the opposite side of the earth from the sun and when it is black it is at the same side. In these positions the pull from the moon and sun is in phase so the tides are maximized.

Answer 4

That really really really long answer did have the information buried in it. Here is a synopsis:

Tides are caused by **differential* gravitational pull; because the moon pulls harder on the near side of the Earth than the far side, from the earth's perspective it is like it is being stretched. While the force of gravity falls off with 1/distance^2, the tidal force falls off with 1/distance^3, so the much closer moon has a larger effect.

With the earth is being "stretched" towards the moon, the rock and slightly 'plastic'(1) parts of the earth are less susceptible to the stretching than the less dense and easier flowing watery film on the surface, so the oceans and atmosphere deform more than the underlying strata in response to lunar tides.

When you picture stretching the water that lies around the globe more than the globe itself, you see why there are two tidal bulges. The Earth then spins underneath these bulges, moving any point on the surface of the Earth through two bulges/day (the near moon side bulge and the far side bulge). The Earth's rotation also drags the bulges a little ahead of the moon's position ( if you draw a line connecting the two bulges and passing through the moon's orbit), with some interesting consequences (gradual slowing of the Earth's rotation and the gradual recession of the moon from the Earth.)

The sun contributes too, but if I recall correctly only about 1/10th as much as the moon. New and full moon tides (when the sun and moon are lines up so their tidal bulges add) are measurably higher than first and third quarter tides but not immensely so.

The second part of your question; the moon is quite small, but so are the tides. What is a few meters compared to the diameter of the earth of over 10 million meters? This is only a deformation of the oceans of order one hundred thousandth of 1%. The scale of the deformation is more a factor of how dense the material in question is rather than anything else. I suspect the atmospheric tidal bulge would be ~1000 times greater than the water bulge, but I don't really know that.

Here are a few pictures to help you visualize tidal bulges.

http://www.slavesofdemocracy.com/bulge.jpg

Naturally the size of the bulge (and the depth of the ocean for that matter) are exaggerated immensely to make the effect visible on the scale of the pictures.

(1) 'Plastic' in the geological "flows slowly" sense, as opposed to the toy industry "made from goopy leftovers of petroleum" sense.

Answer 5

When you compare the distance from the Earth with the size of the Moon it's not that far away. In other words if you drew a scale drawing the Moon wouldn't look that it was very far away. (If the Moon was drawn as a 1" circle the Earth would be 10ft away.) The gravity of the Moon pulls at the Earth and the water in the seas and oceans causing them to move very slightly. We see this as the tides. The Sun also contributes to some tides as well.

Answer 6

Every particle in the universe affects every other particle in the universe, with the weak, long range, attractive force known as GRAVITY. not only does the earth attract us, but we attract the earth. The bigger the body, the bigger the attraction. In the Earth/Moon system, our (peoples) mass is insignificant, the moon is Billions of Kg, and so is the earth. The moon (because it is smaller) is going round the earth fast enough to keep it out there.
If it was to stop dead (Very unlikely), it would come crashing to earth, because of the gravitational field between the two bodies causing them to attract.
Even though it is all the way out there, it's gravity has a visible effect on the more flexible things on earth, like water, we call it tides. Hope the answer is ok, you can find out the detail in any Physics high school text book.

Answer 7

Tides are slight bulges of the ocean's or Earth's surface that face the Moon and the Sun as the Earth rotates on its axis. There are two lunar and two solar tidal bulges, one on the closest and the other on the farthest side of the Earth. The lunar bulges are a little more than twice the height of the solar bulges. At new and full moon, the Sun and the Moon are aligned, and the lunar and the solar bulges add together for the greatest tidal range. At first- and third-quarter phases of the moon, lunar and solar tides are in opposition, and the tidal range is at a minimum. The tides go through one full cycle (a high and low tide) about once every 12 hours and one full cycle of maximum height (a spring and neap tide) about once every 14 days.

Answer 8

It's the gravity of the moon pulling against the Earth. The moon cannot make an object the size of the Earth move, but the oceans, being fluid, rise up towards the Moon creating high tides.

The only baffling part is why is there two high tides a day? When the moon is creating high tide on one side of the Earth, there's a another high tide on the other side.....

Answer 9

it is extra about an inch a three hundred and sixty 5 days so the moon 500 million years in the past will be closer yet not that a lot. remember the Earth is largely lined through 70% of water, not ninety%. The water degrees were fantastically diverse 500 million years in the past, the contintents were in diverse places, remember the large continents like Pangea (sp). also evolution, it replaced into round 500 million years in the past even as life began to branch out unto land. It replaced into up till that factor, life had stepped ahead no better than micro organism. So through the time life made it is way out of the water, the tides weren't that undesirable for life. it can have even made issues more convenient, better tides allowed life an more convenient vacation to the beaches.

Answer 10

Gravity.
The moons gravitational field pulls at the earth. Of course the earth is much too big and solid to be noticeably affected by this gravity, but the oceans are a fluid, constantly moving entity, and so get pulled and stretched upwards towards the moon, causing high tides.

Answer 11

even though the moon is very small compared to the earth it still has a significant gravitational force. since gravity has an infinite range it still affects us. it does get weaker the further away from the source you are but the moon is not far away enough not to affect somethings on the earth and the only thing which will be able to move due to the gravity are the oceans. but remember that the sun also affects the tides.