Why are almost all stars and planets in the universe spherical with equators and poles but not cubical?
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answers:
nineteenthly say: Because a cube would effectively be eight impossibly high mountains which would collapse into a spheroidal shape. Stars can be somewhat flattened or elongated due to rapid rotation or gravitational pull. It would be possible for a planet to be doughnut shaped but no natural process is likely to lead to one forming thus.
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say: Because “God doesn’t play dice with the universe” (Albert Einstein)
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roderick say: What a very good question?
And I would have to agree with most of the answers it all has to do with gravity
Although not being a astrophysics major and not understanding how all laws of gravity work
the evidence shows from the microbiology all the way to the largest known things in the universe all things seems to be in a spiracle
Shape because of the forces of gravity
A wise man once said to search out the greatness of God would basically be an endless task but it does show that there is a creator who's made such wonderful news for us to wander and ponder over
Keep asking such good questions
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roberto say: the circle/ball is the most uniform & stable object nature creates
round atoms,round electrons
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Zheia say: In the example of Ultima Thule which was recently flown past by the New Horizons spacecraft, it is a very unusual shape. But it looks like it may have formed from 2 spherical objects that have collided or come together in some way. Eventually, as Ultima Thule gathers more material it will eventually become spherical. There are also very small spherical objects within Saturn's rings. Icy bodies become spherical much earlier than rocky bodies.
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Jeffrey K say: Any body big enough for its own gravity to be felt must be spherical. Matter goes to its lowest gravitational potential energy place. A sphere has lower potential energy than any other shape.
If a planet was a cube, its corners would be mountains thousands of miles high. They would fall down and round themselves off.
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Clive say: Because anything that is big enough to have strong gravity will eventually pull everything towards the middle. Even solid rock, given enough time. If a planet is a cube, gravity will eventually pull the corners in and make it round.
There will be reasons why it doesn't end up exactly spherical - the Earth isn't because its spin causes it to bulge a little at the equator - so the term we use is "hydrostatic equilibrium". Which means "as near to spherical as it can get".
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Ronald 7 say: Gravitational Equalibrium
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Sky say: Gravity. Even a planet as small as Pluto (yes, I said planet) with its tiny gravity has enough gravity and enough mass to pull itself into a roughly spherical shape. It's not until objects are down in the size range of Phobos and Deimos, the moons of Mars, that they don't have enough gravity and remain lumpy. Also, during planetary formation, even a tiny planet would have so much heat and melted rock from the period of heavy bombardment, that lava would much more easily be able to flow and form a spherical body because all of it would seek a low point until it cools and can't flow (or can't squish molten rock below).
Stars are nothing but fluid, whether gas, liquid, or plasma, and have no solid structure to hold anything up in any sort of mountainous shape. Even if they did, they have tremendous gravity due to their size. And neutron stars, which are so dense they are made of nothing but neutrons, have so much mass and gravity packed into such a tiny body, a ridge or bump as high as the thickness of a sheet of paper would be the highest mountain range on the entire thing.
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Starrysky say: Even if the rocky crust of the planet found it possible to combat the pull of gravity to have a cube planet, there is a problem breathing on it. The corners and edges would extend out into space. Between them would be six pools of air. Also there would be six oceans in the shape of round puddles at center of each face of the cube.
Pretty hard to live on a planet like that.
Same problem with stars. Even if the gases and plasma and neutron material did not flow into a sphere, the star would have problem staying together. So much more mass would be on the corners and edges, not enough at center of faces. The corners would press down hard to make the center of the star produce more energy to balance. But at each flat face, not enough matter to hold back that energy. So there would be six fountains of plasma, heat and light shooting out into space. These would decrease the overall amount of matter in the star until it stops producing any energy at all and dies.
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D g say: try and make a SQUARE WATER BUBBLE .. see what happens its because nature wants to make things simple forces act a cetain way and pull together particles.. this is spherical
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stephen say: Rotation and gravity over time.
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M say: because the universe is continuous and so is a sphere.
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Gabe say: The object has to be OF A CERTAIN SIZE in order to have ENOUGH gravity to round it. Roughly 800 kilometers across or 5 x 10^20 (5 followed by 20 zero's) kilograms, which is 6.29% of Earth's diameter and 0.00872% of Earth's mass respectively. What the object is made of (ices of water and ammonia as opposed to rock and metal, say) are the reason they are perfectly synched, why there is variation. There's round, rounded/irregular/potato shaped, what other shape(s) do you have in mind? Saturn's moon Mimas is roughly at this threshold. What mass? and how big would the resulting smallest-round-by-gravity world be? I do know the Saturnian moon Mimas is the smallest gravitationally round world in the Solar System (or else Ceres is).{it's a matter of How-round-IS-round?}
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Bill G say: Because gravity pulls everything toward the center.
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JG say: What Bill said.
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Tom S say: Spherical due to gravity, equators because they rotate.
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Morningfox say: If a planet was a cube, then the corners would be very high mountains, thousands of kilometers high. Under the pressure of a mountain that high, granite flows like lava. The mountain would slump down to a supportable height, less than 26 km high. On a planet with radius 6,400 km (like Earth), that's about 0.4% of the radius. Bigger planets have more gravity, so smaller mountains.
Similar logic for stars: gravity pulls down any massive thing that tries to stick out.
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jehen say: Gravity.
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Bill say: Gravity attracts all matter toward the center.
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Nikki say: james h. jeans, physicist, has a formula which shows why objects form balls of mass.
One of Jeans' major discoveries, named "Jeans length", is a critical radius of an interstellar cloud in space. It depends on the temperature, and density of the cloud, and the mass of the particles composing the cloud. A cloud that is smaller than its Jeans length will not have sufficient gravity to overcome the repulsive gas pressure forces and condense to form a star, whereas a cloud that is larger than its Jeans length will collapse.
[formula]
Jeans came up with another version of this equation, called "Jeans mass" or "Jeans instability", that solves for the critical mass a cloud must attain before being able to collapse.
Jeans also helped to discover the "Rayleigh–Jeans law", which relates the energy density of black-body radiation to the temperature of the emission source.
Jeans is also credited with calculating the rate of atmospheric escape from a planet due to kinetic energy of the gas molecules, a process known as "Jeans Escape".
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oneofmagi@rocketmail.com say: Gravity.
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Laurence say: I'm pretty sure it's because the centre of gravity pulls the mass towards the centre, forming a sphere with large objects. Some smaller objects such as asteroids are usually very uneven and bumpy.
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Who say: gravity
(And it aint a good question - you only have to know the basics of gravity to know why they the aint cubical)
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Wylie say: In spite of being all-powerful and able to defy any natural law, God just can't get anything to stay cubical or triangular. He's going to need another day to figure it out.
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wobafetty say: Gravity pulls to a center point and a sphere is the shape formed when everything is pulled as closely to that center as possible. Stars and gas giant planets are usually the more perfect spheres due to the fact that they are gas. Water planets would likely almost just as easily be the same. Although rocky smaller planets with their broader amount of elements be them gas, liquids or solids could be sphere, most often they aren't perfect spheres. If gravity had its way they would be sphere but solid matter holds its ground at least for a bit longer than gas or liquid. A simple case of more solid mass on one side than some others being dragged to the same center point could lead a planet to being unable to form as a perfect sphere. Gravity is a cool force but its not magic. Stick a magnet behind a thin wall and sure it will attract magnetic metals but those metals would never reach that magnet. If a solid tries to reach the center point and is stopped by more solid its not going to reach its destination. If the gravity is strong enough eventually everything would start crumbling and be forced closer. There's a theory that's why our planet isn't perfect. However another theory is that its just a left over bruise created by the cosmetic collision in the past which also lead this planet to having enough of what is needed to create life.
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Rudolph say: Not this again. I mean. Its the gravitational pull of the core that eventually pulls everything together. Creating a ball because its pulling from every possible angle the same amount
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sparrow say: Cube is less stable of a shape.
Corners are bound to break off.
Too many irregularities at the surface of it.
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poldi2 say: http://curious.astro.cornell.edu/copyrig...
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rob say: Science
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Tommy say: Gravity takes rocks and puts it together
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Joseph hola say: In this universe, gravity pulls things to the center, making large stuff spherical or near spherical.
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Stephen24 say: The larger an object becomes the more gravity it produces.
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drake say: The corners of a cubical shaped star will move inward by gravity.
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AdamTheAtheist say: Gravity pulls everything to the center, which creates a sphere.
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Doctor Space say: First, if you accept the current theory, planets begin as disks being pulled by a central core. As each chunk of rock is added, it's gravitational pull is combined with the core. Heat and pressure help it combine to become part of the core. Given time, you have a rocky planet. Gas planets begin in a similar way, but then attract large gases from the surrounding space, or create gases internally as the core combines creating heat.
Now are planets really spherical. No. centrifugal forces eventually cause the final shape of a planet to be flatter torwards the poles and rounder around the equators. Interesting, the further you are from the core, the less the effect of gravity. You weigh less standing on top of a mountain, or flying in an airplane. Some places of earth your weight is adjusted by the altitude of the land.
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Acetek say: gravity
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CarolOklaNola say: Anything with enough mass and is large enough becomes spherical in shape because the forces of gravity AND pressure balance each other. They are equal but opposite forces.
Sphere is the most energy efficient and lowest energy state possible. In a cube, gravitational stresses would attract the corners of the cube toward the center and the gravitational stresses would cause fractures and earth quakes. Gravity would redistribute that NASA and make the cube spherical
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