Why are most planets and stars in the universe round: What gives them this shape?

Live Science writes that no matter how far away a particular planet is and what strange conditions it has, it will most likely have a round shape.

So what makes most celestial objects round? In short, everything is gravity’s fault.

“It’s surprising how many round objects there are in space,” says astrophysicist Anjali Tripathi of NASA’s Exoplanet Research Program.

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This effect is the result of self-gravity, that is, the gravitational pull an object exerts on itself. Once a planet or moon reaches enough mass, its own gravity will roll it into a ball.

As is known, celestial objects in the universe began to form after the Big Bang, approximately 13.8 billion years ago. Then tiny dust particles accumulated and began to circulate in the dust clouds. If the collision was soft enough, the dust particles coalesced with each other. Subsequent clashes created a snowball effect. The more mass the newly formed planet accumulated, the more its gravity increased and the more matter it attracted.

“Such gravity will pull all available matter towards the center of gravity. The process is similar to the kitchen sink, where all the water will flow down the drain. In the case of planets, every particle of matter will try to get as close to this center as possible. As far towards the center of gravity as possible,” says the head of the Center for Scientific Research . European Space Agency ESAC data by Bruno Mesrin.

He explains that planetary bodies will continue to move matter until they find equilibrium—a state in which each point is as close to the center as possible. And the only form that can provide this kind of balance in space is the sphere.

For example, Mercury and Venus are nearly perfect spheres because they are rocky planets that rotate very slowly. Icy planets tend to achieve a nearly perfect sphere, as the ice sheet can spread evenly over the surface.

As you can see, not every planet is an ideal sphere. Gas giants Jupiter and Saturn have bulges on their equators due to their rotation speed. According to NASA, Saturn’s shape resembles a baseball landed on top of it. Even the Earth has a slight convexity of less than 1% due to centrifugal force.

Although the universe is full of spherical celestial bodies, other shapes may also be found in it. Asteroids and comets, for example, can have any shape resulting from collisions and interstellar rotation. For example, Mars has a moon shaped like a giant potato.

Moreover, of the approximately 300 known moons in the solar system, only 20 have the familiar round shape. The explanation for this phenomenon is very simple: all these objects have less mass and therefore there is not enough gravity to equalize their shapes.

Let’s remember that scientists recently answered the question of which planet in the solar system is closest to the Earth, and the answer is not very clear.