Earth, sun , Jupiter, all of them
2006-07-25 16:28:26 · 19 answers · asked by gloribelllebron 2 in Science & Mathematics ➔ Other - Science
Planets are not completely round. They are rounded and have many large jagged surfaces on them due to geological activity such as plate techtonics and shifting of land masses.
There are alot of answers to your question by people WHO AREN'T SCIENCE MAJORS and have no degrees in science- unlike myself - talking about gravity pulling on matter causing things to be round. That is only part of the truth. Think about things as small as ATOMS for example, why are they round?
To answer your question, the Planets, Atoms, the Sun, and even soap bubbles are round for the exact same reason.
NATURAL CONSERVATION OF ENERGY.
Natural occourences and formations ranging from land masses, to BIOLOGICAL ORGANISMS allways take shapes that use the least energy.
A Circle is a perfect shape because it doesn't have angles. Angles require alot of energy to first erect them and then keep them that way. For a very large mass such as a planet, gravity causes all matter to fall towards the center of the mass... IT TAKES ENERGY TO KEEP MATTER FROM FALLING DUE TO THIS GRAVITY. Therefore, in a large mass, the absense of useable energy means that their is no work being downe to prevent Gravity from forcing all matter to the center of the overall mass. No matter how much stuff gets piled on top, the mass will tend to be circular because the circle is the most even distribution of matter and takes the least energy to accomplish.
2006-07-25 16:31:31 · answer #1 · answered by Anonymous · 2⤊ 1⤋
Well, technically they aren't perfectly spherical, they tend to bulge due to the planets rotation. However, the general reason they are round is that gravity causes the material to attract equally toward the center of the mass. Since this attraction is equal in all directions, the shape tends to be spherical. If you imagine a cube that has material attracted towards the center, then you can imagine that the corners are farther away than the faces of the cube. However, if you find the center of a sphere, and draw a line straight out to any point on the sphere, the distance is equal in all directions.
2006-07-25 23:34:24 · answer #2 · answered by Simon Trueheart 2 · 0⤊ 0⤋
Planets - and stars, such as the sun - are massive enough to have significant gravitation. That gravity pulls the matter of the planet towards the centre of mass... so it tends to form a spherical collection, centred on the center of mass/gravity...
Thus, a "round" body
To be stricty accurate, many are not quite spherical, becasue of other effects at work... spin, for example, tends to make the earth "bulge" towards the equator, making it an "oblate spheroid"... a sphere that's been sat on, near the poles :-)
2006-07-25 23:38:45 · answer #3 · answered by IanP 6 · 0⤊ 0⤋
Because gravity pulls on its peaks and flattens them out. A square planet would disintegrate into a round planet because its peaks (corners) would fall apart; that is, if the planet is large enough.
Some astronomers want to use this as the definition of a planet. If it is big enough to flatten all the peaks, then it is a planet; else it isn't. Unfortunately, this produces too many planets - about 30 of them. Miranda, Rhea, the Moon, Pluto, Xena, and even Ceres would all be planets.
2006-07-25 23:34:19 · answer #4 · answered by alnitaka 4 · 0⤊ 0⤋
Planets are actually eliptical because they are spinning (an elipse is round, but not a perfect sphere).
The reason that they are round is because gravity draws the matter in to a single point; the matter (sand, lava, gas etc.the stuff of planets) squishes in around the center of the gravity equally and forms a close approximation of a sphere.
2006-07-26 01:54:48 · answer #5 · answered by Bernard B 3 · 0⤊ 0⤋
Some of the asteroids are not round, i.e. like globes. When the center of a planet acts like a liquid instead of a solid, which happens even to rock materials under enough heat and pressure, then planets act just like drops of water and become round. Gaining insights about scientific physics and subjects like gravitation is exciting, you know.
2006-07-25 23:52:20 · answer #6 · answered by hrdwarehobbyist 2 · 0⤊ 0⤋
Part is rotation on their axis, part is rotation about the sun.
A spherical (or actually a flattened oblate) roates better and is easier in the creation of the planet.
Ever seen a square planet? (Htrae does not count for you Bizarro World fans)
2006-07-25 23:33:01 · answer #7 · answered by Anonymous · 0⤊ 0⤋
the law of gravity explains why there are all round, as well as stars and natural satellites. Sorry T. Friedman, in this field the World is still round
2006-07-25 23:33:01 · answer #8 · answered by bonee 3 · 0⤊ 0⤋
Gravity at the core of each object in the Universe tends to make it that shape.
And if that is not good enough - the answer to everything, life and and the universe is 42.
2006-07-25 23:31:45 · answer #9 · answered by Sirena 5 · 0⤊ 0⤋
Gravity, and the fact that nature tends towards stable configurations.
In a way, the reason is similar to why bubbles are spherical.
2006-07-25 23:34:18 · answer #10 · answered by l00kiehereu 4 · 0⤊ 0⤋