Why are all the planets, then sun and moons round like ball shape not rocky shapes.?
341419
Yes, Planets are generally spheres, not cubes or cylinders or odd shapes. Some small galactic bodies such as asteroids comets do have odd shapes, but planets, suns and stars and even moons look like spheres. That's because, when they were formed millions of years ago, they were essentially molten liquid.  Gravity and meniscus forces (surface tension) cause the object to take on a rounded shape--and it cools in that position.  In addition, the nature of gravity will pull uniformily toward the center--as the distance from the center increases, so does the gravitational force. You can think of gravity as a force that points inward toward the center of all things that have mass-- so that every part of the surface (especially liquids)is pulled evenly toward the center, resulting in a spherical shape.\n\nPlanets are not perfect spheres because there are other forces acting on the planets too which are trying to stretch them.  Because they were once hot moltent liquid, they buldge in the middle.  Earth and the moon reflect this phenomina.   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. \n\nNote that planets and moons had to be a liquid or they would not have been able to escape the gravitational force of the nearest larger body.  Remember that liquid will seek the path of least resistance as it moves.  In otherwords, an impact on the earth would cause a splash of moltent material that could escape the earth's atmosphere at the exact angle (path of least resistance) to be able to exit the planet's atmosphere without burning up.  Once it exits into space, the gravitational pull of the larger body will pull it into orbit. It will stay in orbit until it is acted upon by a larger force.   Fortunately, we haven't seen any larger forces since the earth was created and therefore, the conditions will remain for millions of years into the future.
114224
Only bodies with a large gravitational mass are round. There is enough gravity to pack it more tightly and this combined with roation of the object forms a round shape. Smaller objects like asteroids, comets and small moons often have irregular shape because there was not enough gravitational mass to compress the object into a round shape
425798
Our planet earth and for that matter all planets, moons and stars are generally spheres, not cubes or cylinders or odd shapes. Some small galactic bodies such as asteroids comets do have odd shapes, but planets, suns and stars and even moons look like spheres. That's because, when they were formed millions of years ago, they were essentially molten liquid. Gravity and meniscus forces (surface tension) cause the object to take on a rounded shape--and it cools in that position. Do you remember seeing astronauts squeezing out juice or other liquids, they immediately become round in space.  It is the nature of gravity too pull uniformily toward the center--as the distance from the center increases, so does the gravitational force. You can think of gravity as a force that points inward toward the center of all things that have mass-- so that every part of the surface (especially liquids)is pulled evenly toward the center, resulting in a spherical shape.\n\nPlanets are not perfect spheres because there are other forces acting on the planets too which are trying to stretch them--rotational forces, etc. Because they were once hot moltent liquid, they buldge in the middle for these secondary centrifigal forces. Earth and the moon reflect this phenomina. 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. \n\nNote that planets and moons had to be a liquid or they would not have been able to escape the gravitational force of the nearest larger body. Remember that liquid will seek the path of least resistance as it moves. In otherwords, an impact on the earth would cause a splash of moltent material that could escape the earth's atmosphere at the exact angle (path of least resistance) to be able to exit the planet's atmosphere without burning up. Once it exits into space, the gravitational pull of the larger body will pull it into orbit. It will stay in orbit until it is acted upon by a larger force. Fortunately, we haven't seen any larger forces since the earth was created and therefore, the conditions will remain for millions of years into the future.
884425
well the path of the planets is different for each due to the size but the are similar to a oval type shape, gravity hold the planets in orbit and as far as the asteroids they are freely moving until caught by a gravitational pull of a larger object
34520
Gravity shapes objects.  If an objects mass is over a certain threshold then gravity will be strong enough to overcome molecular forces to "mold" an object.  Most asteriods have masses that are too low for this however planets and most moons are massive enough.  \n\nWhy a sphere?  This is due to the inverse radial dependance of the gravitational force.  In order words at a given distance from the center of mass distribution the force of gravity is the same.  This type of shape is a sphere.
758796
First of all it is a significant body.  At one time it was geologically active therefore had a molten interior and rotation similar to the earth.  Over time due to the combination of gravity, rotation and geological activity the moon developed a round shape.  The moon has long since been "dead" and its rotation slowed due to the earths gravitonal pull so now its rotational period precisely matches it revolution around the Earth.
111203
I think the current theory is that it comes from the origin of the solar system as a spinning mass of material. This material had a certain angular momentum, which was retained as the material coalesced into the sun and the planets and moons and other bodies. So there are only a few planets and moons whose orbital and rotational angular momentum vectors are not aligned with each other (like Neptune, and Venus, Triton and a few of the smaller, more distant moons of Jupiter and Saturn).
1069004
For the most part, the atmosphere moves along with the surface of the earth. On the other hand, winds going in any direction tend to grind down mountain peaks.\n\nHowever, if the Earth were not fairly close to round, then the molten lava inside the earth would rupture the crust and deform the earth into a round shape. The main reason the Earth is round is gravity, not wind.
337086
The planets are actually trying to move in a straight line at a high speed due to the intertia from some force long ago.  When two objects are moving by each other, their gravity interacts and pulls them toward each other, bending the path that would otherwise be a straight line.  If they are too massive and too close, the gravity pulls them so much that they collide.  If things are balanced just right, the path is bent into a complete ellipse.  It's an ellipse instead of a circle because the sun is actually also being pulled a tiny bit toward the earth, as well.\n\nYou could consider gravity to be sort of a "perpendicular inertia", and the planets would revolve around the sun FOREVER if there were no other forces involved.
623067
Yes, Earth is the third planet from the sun.\n\nNo, Earth is not an exact sphere.  The Earth ispudgy.  It has a slight "bulge" around the Equator.  We're close enough, and we're certainly not flat, but we're not on a perfectly round planet.\n\nThe planets in the solar system are (in order from sun, outwards):\n\nMercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, & Pluto.  There is also an arguable "10th planet", but until NASA names it (and confirms it's a PLANET, not just a rock) I'll say there's nine.\n\nAlso, in between Mars & Jupiter is the Astroid Belt, which some think was once a planet that exploded long ago.\n\nFor (really) in-depth information, visit Wikipedia:
711289
Actually, those circles are NOT perfect.  They're slighly elliptical.  This is called the excentricity of the orbit.  \n\nBut, yeah, they are more or less on circles, and that's because they want to go straight forward (inertia) but the pull of the Sun's gravity stops them from goind away.\n\nIt like tieing a ball on a rope and turning it around.  It makes a circle.  Let go of the rope, and it will go on a straigt line.  The rope is the Sun's gravity.
366583
This is because of their centre of gravity.\n\nAll of their constituent mass is  pulled with an even force into the centre of the object....thus the surface of the celestial body is equidistant from the centre...ie. almost spherical.\n\nMany are in fact oval due to the fact that they spin around. This moves some of the mass to the equator of the object....rightly due to centrifugal force.
551432
It's just an assumption...\n\ncoz it looks like a sphere... like how the moon looks round...\n\nBut can u be sure!!!
517320
The sun is spherical for the same reason most large astronomical bodies are spherical - gravity. \n\nGravity will pull equally on all parts of a body, so every part of it will try to get as close to the center as possible.  As astronomical bodies form and coalesce, they move closer to the center until the opposing pressure (for example, from being solid like the earth, or the pressure of nuclear radiation as is found in the sun) equals the force of gravity.  Since every part of the sun is trying to collapse in equally, every part of the sun's (earth's, other planets', other stars') becomes equidistant from the center.  Which is the definition of a sphere!\n\nNote that not all astronomical bodies are perfect spheres, though!  Small objects - say, like the moons of Mars - don't have enough gravity to pull themselves into a spherical shape.  And some bodies have other forces coming into play.  For example, Jupiter is spinning so fast (once every 10 hours) that it bulgest out 4,300 km at it's equator due to centrifugal force.  This happens with the earth, too - the earth is 22 km fatter at its equator due to centrifugal force.
862988
Earth and the other planets were formed from a giant cloud of gas and dust revolving around the primitive sun. As in any other moving fluid, local whirlpools kept appearing and disappearing all the time. \nAs the cloud started to cool, local perturbations caused density variations : some whirlpools got lumpier than others, just as in a bowl of porridge when it cools off. They thus grew more stable and accumulated more matter because of their increasing gravity. On further cooling, these separated out as planets, molten globes of matter still spinning furiously.\nEven when the planets solidified at last, they retained a part of their original spin. That's why the Earth and the other planets are still spinning around their axes. That's what, thankfully for us, creates days and nights.
572633
Aren't the rings about planets just the debris that is spinning around them? If so, then not every planet has a ring because they don't all have space junk that is part of their gravitational field.
292052
That's a really good question, that doesn't have an answer yet.  The current theory of solar system formation suggests that planets spin in coordination with the orbital spin of the disk of matter that forms the core of the solar system.  The spin of the accretion disk itself is the result of conservation of angular momentum, and can either be clockwise or counter-clockwise, which would be a relatively random process.\n\nThere are 'accidents' however, whereby planets are impacted by other large bodies in random ways and can greatly skew the planetary orbit and/or spin.\n\nSometimes the results are really weird, such as Uranus, which rotates top-to-bottom relative to the plane of our solar system.\n\nFrankly, until we're able to do a survey of planets in our galaxy and a few others, I think it would be hard to guess what the real averages would look like, and whether or not they are random.