when all the planets were created why the shape of each planet like earth or star like sun became circle?

Asked by  | 6th Mar, 2012, 10:45: PM

Expert Answer:

The reason planets and stars appear spherical is because gravity compresses the planet into a shape that most evenly distributes the gravitational force among the planet’s mass. Nature seeks to minimize the surface area needed to contain a given volume, and the shape that keeps volume at the absolute minimum is a sphere. Any object in weightless space larger than a couple of hundred miles in diameter has enough mass for its gravity to overcome large-scale irregularities and force it into a spherical shape. This gravitational compression also generates significant amounts of heat at the center of the planet. This heat melts, or at least softens, any solid materials within the planet, facilitating the planet’s collapse into a spherical shape.
However, the planets and stars are not perfect spheres. Almost everything in space rotates, and rotating a non-rigid sphere causes it to bulge at its equator from the centrifugal forces acting on it. This spinning distorts large planets into a slightly squashed shape. Hence a planet’s diameter measured through its poles is smaller than the diameter measured through its equator.
(Objects in space smaller than about 100 miles in diameter, such as most asteroids, comet nuclei and small moons, lack the mass to create a gravitational field strong enough to compress themselves into spheres.)

Answered by  | 7th Mar, 2012, 09:10: AM

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