why is the world round?

Question

why no cube or rectange or triangle

Answer 1

because it would affect gravity and life as you know it would not exist. If the axis of the earth wasn't tilted life would not exist

Answer 2

All matter has a gravitational field asociated with it. The larger the mass, the stronger the gravity. A large mass such as the Earth (or indeed any of the planets or their major satellites) produces a relatively strong gravitational field which exerts an attractive force on any other mass in the vicinity. In the absence of any other forces each individual piece of mass will be pulled as close to the centre of the Earth's mass as possible.

Imagine for a minute that you started off with a bizarre earth-sized planet shaped like a tetrahedron (a 3 dimensional triangle) or like a cube. The corners would be enormous mountains sticking far above the atmosphere into space. They would be very unstable and the slopes would crumble under their own weight whilst the rock inside them would, under the huge pressures and temperatures, flow inwards/downwards towards the centre of mass of the planet. Eventually the terahedron and the cube would both become spheres or something approximating to them.

Only small masses could have a non-spherical shape - as is the case with many asteroids although they're much more likely to be potato-shaped than any regular geometric shape.

Answer 3

Well, first of all, it has to be a three-dimensional solid, agreed? Then think about what gravity would do to a cube or box shape or anything with corners; while the planet was still forming, the gravity coalesced on a specific point, necessarily because gravity pulls in all directions at the same time. So while it was still pretty fluid and flexible, it was condensed into a sphere because that is the only shape that has a surface which is the same distance from the center (of gravity) all around. Corners would not be able to form.

Answer 4

The reason why the earth is round comes down to our dear friend gravity. Gravity pulls with equal strength in all
directions. What this means is that any variations from a spherical shape will lead to gravitational forces thatbring the shape back into that of a sphere.

If an object has enough mass it will pull iself into a sphere. This is why there are asteroids out there that not perfect circles. It is because those objects do not have enough mass and therefore not enough gravity to pull itself into a sphere.

The earth however is not perfectly round.The rotation of the earth is fast enough to cause centrifugal effects, which cause the earth to bulge slightly at its equator and flatten slightly at its poles. This is because rotation flings matter outwards, weakening gravity there by a fraction of 1%. Another example of this effect is with Jupiter.

Jupiter spins faster than Earth, just under 10 hours compared to Earths 24 and bulges much more. Telescope pictures of Jupiter show it visibly fatter at the equator.

Answer 5

Because every heavenly body is in spherical shape. This is the most energy efficient shape for something under gravitational force. Just like a drop of water would drop in a straight line in the air or flow along a curved line on a spherical surface.

Answer 6

That's easy. It's because of the gravitational pull of equal strengths in all directions creating a spherical or 'round' shape. Centrigual forces as the earth is spinning is pulled back to the into a sphere by gravity.

Answer 7

Due to its spin, the Earth's original "not-so-round" shape eventually became more round as it is a more aerodynamical shape for sustaining the spin.

Note: The top and bottom of the Earth however, are flat, and so the shape of our Earth is not a sphere, but a geoid.

Answer 8

Earth was completely liquid when its shape was formed by its own gravity. It's similiar to (but not the same as) dropping a drop of water in a glass of oil. As the surface tension of the water attempts to minimize the volume of the water into a sphere, so too did gravity pull all Earth matter as close to its center as possible.

PS - that's "oblate" spheroid, not "oblique"

Answer 9

Its an oblate spheroid. It was caused because the formation of the universe, causing the planets to be round, and them having elliptical orbits.

Answer 10

The shape has to do with the strength of the gravitational forces. Many asteroids have odd shapes, but as they get larger, they tend to round out.

Answer 11

It spins - any large chunks will have been smoothed off.

Also, the planet forms as it cools and the matter is distributed uniformly due to the effects of gravity affecting all matter equally (ok, apply the inverse square law if you know physics)