Shouldn't gravity be better described as the ZONE of gravity? Consider the earth. It isn't a perfect sphere, so gravity can't be a point. How about a potato shaped object. What about two planets that have joined? I understand that this can't happen but they are MY planets and they are joined together.

For irregularly-shaped objects, it is easy to calculate a CENTER of gravity.

Why could two planets not be joined? Some theories of the origin of some planets are that two planets (or a planet and a very large asteroid, or a planet and its sub-planet, or moon). By the way, the orbital path of a planet and a moon is based on the center of gravity of the two bodies, not the center of the bigger of the two bodies.

babthrower is right.

NASA even landed a spacecraft on an asteroid that is shaped like a potato squeezed in the middle. It was a very difficult caculation, but they proved it's possible to do it.

Gravity is only considered a point source when doing simple calcuations, in reality, with the earth and other objects, gravity is stronger in some places than it is in others.

check out this site on mapping earths gravity:
GRACE
and see a pic of how earths gravity differs
HERE

-Chris

Thanks Chris. I see that I should have called it a gravity field, not a Zone of gravity. I'm asking if there is a three dimensional field of gravity within the earth. Maybe the center of gravity will be a point some where within this field to a point on the earths surface. And so on. On a larger scale, I guess that the shape of ALL gravity is the shape and size of the universe.

Lee

Thanks Bibc. I should have used the term "gravitational field". What I am trying to visualize is a three dimensional shape inside the earth that is this field. What I visualize is a straight line from a point on Earth to somewhere in this field. Every point on Earth will have its own line. I'm thinking that your link is not opposed to my idea. Would the total shape of all gravity be the shape and size of the universe?
Or am I wasting my time thinking of such nonsense?

Lee

If you go to the center of the earth, you will find that you will just float there, since gravity fields will be cancelled out by the 'pull' (in the Newton classical sense) of the earth in all directions radially outward from the center of that assumed sphere.

In modern day Physics, Gravity is the curvature of space-time in the presence of mass. So at the center of the earth, space-time is essentially flat. You are right on with the shape of the universe being the shape of gravity. The Universe is essentially flat, but with ripples (gravity wells) in it near mass. So there's a wrinkle in the space-time fabric near an apple, and near the moon, and near the earth, and near the sun, and near the stars, etc., and overall , a ripple in the universe itself, shaped by the mysterious Gravity.