# Can Earth be taken as a uniform sphere? [closed]

A sphere is Uniform if it's mass is distributed all over the surface. Can we say Earth is Uniform sphere?

• Perhaps this Wikipedia page on the Structure of the Earth will provide you with the detail for this. But for some purposes you can approximate Earth was a uniform sphere - it's going to depend on what accuracy you require. – StephenG Oct 19 '17 at 11:10
• -1. Unclear because no context is provided. Also no effort is made to answer the question. We can "explain" a confusion, but you have not "explained" why you are unable to answer the question yourself. – sammy gerbil Oct 19 '17 at 11:57

Just as @Petroglyph said, the mass distribution is not uniform for earth.

I would like to add that the shape of the earth is also not an ideal sphere due to the rotation of the earth about its own axis. In fact, the earth takes on a more "flattened" shape. You could read more about the equatorial bulge if that is what you are asking. But for simplicity, you can take a look at this video https://www.youtube.com/watch?v=Tctr8CIMOZA .

Basically, the portions of the earth near the equator experience larger centrifugal force and tends to move outwards away from the centre of the axis of rotation more than the other portions of the earth.

Not sure if this is what you are asking but hope this helps.

I am not quite certain, what the context of the question is but will attempt an answer anyway. If you provide more information, I will change it accordingly.

Strictly the earth cannot be considered as a uniform sphere, because a lot of its mass is concentrated in the core and the surrounding material. So if anything, it can be considered as a ball of uniform mass.

This too is not correct, because the mass distribution is not uniform and the earth is not a perfect ball. But it is a reasonable approximation for some easy calculations. But all of this only matters, if you check the gravitational field inside the earth or on its surface.

If you calculate the gravitational field for these objects when you are far away from them, they all look like a point mass. So in this case one could say that the earth is a uniform sphere or ball.

If you are interested in the calculation to show this, I can provide it later.

As petroglyph said, it depends on the context. For little space, such as working in a laboratory or in a citiy, you can even consider not as a sphere but a plane. And if you consider stellar magnitudes you can treat Earth just as a point.