why are planents round?

Answer 1

It has nothing at all to do with gravity. Masses of fluid stay together because of a force called molecular cohesion.

Celestial bodies condensed from gaseous or fluid states, and gasses and fluids always assume a spherical or near spherical shape when unconstrained. Raindrops are the classic example, though raindrops take on a "pointed tail" because they are flying through the air and the slipstream pushes them into a somewhat elongated shape with that trailing point.

The reason all these celestial objects assume a spherical shape is the basic geometric principle to the effect that a sphere is the shape that allows the greatest internal volume with the least surface area.

Answer 2

Planets seem to be spheres, not cubes or cylinders or oddball rocky shapes. Some smaller bodies such as asteroids or Mars moons Phobos and Deimos, do have odd shapes, but larger bodies like the nine planets and most of their moons do look like spheres. That's because of the nature of gravity. You can think of gravity as a force that points inward toward the center of the planet so that every part of the surface is pulled evenly toward the center, resulting in a spherical shape.
Of course, planets are not perfect spheres because mountains and valleys and even skyscrapers are all deviations from the spherical shape. However, as planets get larger, gravity gets stronger, until eventually large objects on the surface are crushed under their own weight. That's why we don't have mountains that are 50 miles high or skyscrapers that are 2,000 stories tall. Planets stay basically spherical because any large deviations get crushed.

Although gravity keeps planets close to spherical, there are other forces that cause deviations from the basic spherical shape. For example, the rotation of the earth once every 24 hours, causes an apparent centrifugal force which creates a bulge at the equator. In fact the earth's diameter at the equator is 7,926 miles while the diameter between the poles is only 7,900.

Answer 3

Gravity doesn't like pointy bits. When something sticks up too high (like a mountain), gravity likes to pull it down. When there's a deep indentation, gravity tends to fill it up with debris.

The only shape where nothing sticks up and nothing dips in, is a sphere.

If an object is fairly small (like an asteroid, only a few miles across), its gravity is not strong enough to counteract the strength of the rock; so pointy bits are allowed there. That's why many asteroids are distinctly NOT round.

But in a large body like the earth, the gravity is strong enough that it more or less equalizes the height of everything. That's why there are no mountains that are 20 miles high--they would just sink under their own weight.

Answer 4

I like to think this has to do with Gravity, the planet's spin, and the fact that the medium the planet is in, is a vacuum.

Gravity tends to pull everything to the densest part, the core of the planet/object.
But Gravity really isn't as strong a force as we are led to believe. Electro-magnetism and the strong and weak nuclear forces are many more times as strong and can counteract gravity in the right situation.
If a square spins on an axis eventually the edges will "wear off"(actually not much is lost in this situation, the matierial is still there) due to erosion and centrifigul force. The Earth is spinning very fast and has been doing so for many, many thousands of years.
Lastly the earth itself is inside the vacuum of space. This is hard to describe, but vacuums tend to create "bubbles" of matter. Liquids in a vacuum are forced into a spherical shape, Though solids tend to keep thier shape they are constantly having the force of vaccuum upon them, trying to force them into a spherical shape.

Answer 5

it is because the planets are formed by gases, and when they are formed the gases try to have the smallest surface area as possible , as circle has the smallest surface area therefore the planets are in a round (spherical) shape.

Answer 6

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Answer 7

Gravity.

A sphere is the most compact geometric shape. That's why raindrops and teardrops and soap bubbles are round, too.

Answer 8

Not all planets are round. Well, since they took Pluto off the list, maybe they are...

Answer 9

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