Why is the earth a sphere???

Question

This is for my younger sister's homework or something. Well, any helpful responses willl be appreciated.
Best Answer to a good one.

Answer 1

Because of gravity. To put it simply; when you put equal pressure on an object on all sides, what happens? It compresses into a sphere.

Answer 2

Technically speaking, the Earth is an "oblate spheroid." That means it's a little flatter on the poles than a sphere. The reason for the shape is that when matter started accreting in space (space junk spinning around other space junk attracted by each others' respective gravity), it took the spherical shape because it is simply the most efficient form for the mass involved (check out film of astronauts playing with liquids in orbit - in zero G it all forms a sphere).

Answer 3

Gravity.

Part of what defines a planet is a spherical shape. After an object is several hundred miles in diameter, the objects own gravity will start shifting the mass around, until it becomes spherical.

Answer 4

Think of it this way. Suppose the earth were a cube. Then some points on its surface would be farther away from the center than others. The corners, for example, would be much farther out than the rest.

Answer 5

because of earth's gravity the pulling gets even around the world to make it a sphere not a square

Answer 6

There are several reasonable ways to approximate Earth's shape as a sphere. Each preserves a different feature of the true Earth in order to compute the radius of the spherical model. All examples in this section assume the WGS 84 datum, with an equatorial radius "a" of 6,378.137 km and a polar radius "b" of 6,356.752 km.

* Preserve the equatorial circumference. This is simplest, being a sphere with circumference identical to the equatorial circumference of the real Earth. Since the circumference is the same, so is the radius, at 6,378.137 km.
* Preserve the lengths of meridians. This requires an elliptic integral to find, given the polar and equatorial radii: \frac{2a}{\pi}\int_{0}^{\frac{\pi}{2}}\sqrt{\cos^2\phi + \frac{b^2}{a^2}\sin^2 \phi}\,d\phi. A sphere preserving the lengths of meridians has a rectifying radius of 6,367.449 km. This can be approximated using the elliptical quadratic mean: \sqrt{\frac{a^2+b^2}{2}}\,\!, about 6,367.454 km.
* Preserve the average circumference. As there are different ways to define an ellipsoid's average circumference (radius vs. arcradius/radius of curvature; elliptically fixed vs. ellipsoidally "fluid"; different integration intervals for quadrant-based geodetic circumferences), there is no definitive, "absolute average circumference". The ellipsoidal quadratic mean is one simple model: \sqrt{\frac{3a^2+b^2}{4}}\,\!, giving a spherical radius of 6,372.798 km.
* Preserve the surface area of the real Earth. This gives the authalic radius: \sqrt{\frac{a^2+\frac{ab^2}{\sqrt{a^2-b^2}}\ln{(\frac{a+\sqrt{a^2-b^2}}b)}}{2}}\,\!, or 6,371.007 km.
* Preserve the volume of the real Earth. This volumetric radius is computed as: \sqrt[3]{a^2b}, or 6371.001 km.

Note that the authalic and volumetric spheres have radii that differ by less than 7 meters, yet both preserve important properties. Hence both are common and occasionally an average of the two is used.

Answer 7

The magnetic field of the earth creates an equilibrium distribution of matter.

Answer 8

Its spherical cuz this shape requires the least amount of energy to hold. The spining and gravity creates this also.

Answer 9

Hi. Gravity pulls everything towards the center.

Answer 10

God wanted it to be that way!!!!!

Genesis 1:1
God created the heavens and the earth. If you are not Christian try reading a The Bible. it has really cool stuff in it.