Why are almost all stars and planets in the universe spherical?
-------------------------------------------------------
answers:
aladdinwa say: Not "almost"; "All". All stars and planets in the universe are spherical because, by definition, a celestial object MUST have enough mass to have enough internal gravity to pull itself into a spherical shape before it can even be classified as a planet.
The technical term is "hydrostatic equilibrium". Google it.
-
goring say: So that the Gravity power at its surface would be the same.Hence invariant in all direction.
-
anand say: The gravitational pull within the s
-
nineteenthly say: Because above a certain deviation, an irregularity would constitute a very high mountain or deep valley or other depression which would level out due to gravity. A doughnut-shaped planet is theoretically possible and massive rapidly rotating gas giants are squashed. Also, close binaries are pulled into prolate spheroids by each others' gravity.
-
Clive say: For the very simple reason that if ANYTHING is big enough, its own gravity will pull it into this shape. Everything gets pulled towards the middle, and the shape where everything is closest to the middle is a sphere.
This is part of the definition of a planet. There are three conditions that make something a planet and one of those is that it is in hydrostatic equilibrium. Which means that it is big enough for this to have happened. Maybe it's not exactly spherical because it's spinning, so it will bulge in the middle, so that's why we say "in hydrostatic equilibrium" instead of "spherical".
If an object is too small to have achieved this, like an asteroid or a comet, then it won't be smoothly rounded like a planet.
-
Jim Moor say: Because they are like soap bubbles! And soap bubbles are round
-
Ronald 7 say: Angular Momentum
AKA Gravity
-
Will say: Take a physics class.
-
say: Because gravity pulls things down in a roundish way.
-
Richard say: According to the laws of physics, an array of materials will try to rearrange itself so that each piece of the materials will get as close together as possible. That is why they become spherical.
-
brian say: Because of the even gravitational pull from every direction which clumps to form a sphere.
-
say: efficiency of the sphere and close approximation of viable matter, collects neatly.
-
The Donald say: God likes round.
-
geezer say: Basically .. Gravity.
-
Gray Bold say: Gravitational collapse is the contraction of an astronomical object due to the influence of its own gravity, which tends to draw matter inward toward the center of gravty. Gravitational collapse is a fundamental mechanism for structure formation in the universe. Over time an initial, relatively smooth distribution of matter will collapse to form pockets of higher density, typically creating a hierarchy of condensed structures such as clusters of galaxies, stellar groups, stars and planets.
-
Tom S say: Gravity works the same throughout the universe.
-
D g say: its because of gravity ... think of gravity as a force but also the objects push apart when they hit each otehr or another force repels them like say two electrons getting close together will push apart.
when the two forces are EQUAL the object is STABLE OR in static equilibrium
if you bring two sall grains of dust together they will never be completely stable shape because they form a line and if a force acts on one particle the other will move and pull the other
but when you have three they will form a shape that allows all three objects to be the same distance apart
if they are numbered 1 2 and 3 then
d12 would equal d23 ... would equal d31
i think the shape they form is a flat triangle ...
it gets really interesting when a 4th particle is added ..
then we have a pyramid shape i forget the technical term for it ...
with the 4 particles being 1 2 3 and 4
d12 = d13 = d14 = d23 = d24 = d34
this forms a pyramid that has 4 equal sized tringles for sides ..
then when a 5 particle is added the shape gets more complicated and rounder and so on and keeps going until there are many many partcles and these form a sphere fo sorts
-
Johnny say: Because they'd be pretty boring if they were square
-
quantumclaustrophobe say: A sphere is the shape with the least potential energy a mass can assume. When there are no valleys to fill up, no mountains to fall down, when the whole mass is within some, minimum radius, the potential energy at the surface is near zero.
-
say: The sphere has the smallest surface area to volume ratio, so it’s the most efficient shape.
-
Country Boy say: They're not. Look-up the shape of Mars Moon Deimos.
-
? say: Because that is how they were ORBganized...get it?!
-
Kevin7 say: It is the influence of gravity
-
Adullah M say: Have yo ever seen any kind of fruits on earth having square or rectangle shape , I wonder.
-
Bill-M say: NOT Almost. All of them are. When a body reaches a certain Size, Gravity takes over and shapes it into a ball.
-
jehen say: Not almost all. All. Because of the force of Gravity. There are irregularly shaped rocks up there, but they are too small for gravity to have done the work of making them spherical
-
Climate Realist say: Hydrostatic equilibrium
-
say: Gravity is the short answer. A longer answer would only confuse you.
-
Good Man say: All are made of mud and sand with stones
-
Nikša say: Sphere represents female polarity, impregnated by the square core. It's a balanced state, equidistant.
-
diamond say: That's just how God made them
-
say: because they are like seagulls; they fly everywhere and leave poop everywhere as well
-
say: it has a smalle surface are to volume ratio and therefore is the most efficient
-
Acetek say: gravity and they are all spherical. every single one of them
-
CarolOklaNola say: Equal and opposite forces, gravity AND PRESSURE. Main sequence Stars and planets are in hydrostatic equilibrium. Angular momentum IS NOT the reason
A sphere is the lowest energy state an contains the maximum amount of volume in the smallest surface area possible.
WHY am I the ONLY one who mentions the force of PRESSURE?
-
Luca say: Physical systems always try to reach the configuration that minimize potential energy. In the case of gravity, this configuration is a sphere. If the body is also rotating there's an axial contribution and the shape becomes a bit flat in the rotation plane.
-