# A Matter of utmost gravity.

Where is the Earths
gravity the strongest?
If I were floating about WAY out in space, the gravity from the Earth would be very small. If I were in the middle of the Earth the gravity would be zero. Somewhere in between, the Earths gravity
must reach a maximum and then taper off. Where? Sea level? Mountain tops?
Is there any way to measure this?

If we assume that the Earth is a sphere, then that’ll make the answer simpler, so I’ll do that.

If the Earth were uniform density, the gravity would be max at the surface, and drop linearly to zero as you went further down. So halfway down, the gravity would be halved, etc.

The Earth in reality is not a uniform density - the core is denser than the outer part, the mantle. I don’t know enough about the exact distribution to answer the question, but I seem to recall that the gravity is roughly constant from the surface of Earth to the surface of the core, and then it starts dropping off once you get inside the core.

Achernar is right, of course. But the earth is not a perfect sphere, so whichever point on the surface that’s closest to the center of the earth should have the strongest gravity. The earth is close to being an oblate ellipsoid (slightly squashed from the top/bottom), and the south pole is on land at a high elevation, so the north pole is probably as close as you can get to the center of the earth.

There’s also centrifugal force which counteracts the gravitational force at the equator. This is minimized at the poles so, again, the north pole should be it.

But I suspect there are some places with unusually high density rock beneath the surface. Those places may have a stronger gravity than the north pole. (I’m an astronomer not a geologist, I don’t know much about small features like that…)

And welcome to the board. Good question.

But since the Earth bulges at the equator, and is flattened at the poles there is more mass under one’s feet at the equator. Experimentally, it has been determined that the gravity at the poles is slightly stronger than at the equator, but is this due to the earth’s rotation, or to the fact that one is closer to the Earth’s center at the poles? I’d do the math, but it’s late

http://www.cnn.com/TECH/space/specials/scenes/2001/11/27/gravity.map.jpg

Highly exagerated.

That looks like a bruised butt.

It’s strongest at the Mystery Spots! You can see water running uphill!

Gravity is a function of mass.

Since we would measure mass between the Earth’s geometric center and the point on the surface farthest away from the center, I would wager the maximum gravity would be measured at the peak of Everest (this of course not taking into account centrigugal action generated by earth’s rotation).

And the inverse square of distance.

I don’t think this works all that well. It seems to imply that an object with a hole through its center would magically exert reduced (or no) force on another object aligned with the hole.

I don’t agree with your logic, but I’m posting to point out the inaccuracy of your facts.

The peak of Mt. Everest is not the farthest point from the center of the Earth. The peak of Mt. Chimborazo is.