The Space is vast. Once you realize how big our mother galaxy is, and how many billions of galaxies are present there, you’ll know how tiny we are.
We all have looked into the day and the night sky. We have seen the Sun, the Moon, and maybe on some occasions, other planets of our solar system, with our without a telescope.
But have you noticed something very similar about them? All galactic bodies are spheres or round. They aren’t a cube or a pyramid or flat (damn you flat earthers), but spheres. Why are they spheres?
There are eight planets in our solar system (I miss you, Pluto). They all differ in a lot of ways. Be it their size, their distance from the Sun, some of them are full of gasses, Jupiter and Saturn are so big, mercury is so small, there’s life, air, and water on earth, others are ghostly. But they’re all nice and round.
Let’s first talk about how planets are created. They form when the material in space starts colliding or bump together. After a few million years they are big enough that they have a good amount of gravity. Gravity is the force that holds all the stuff together in space. When a planet gets big enough, it will start to clear whatever comes in its path around the star it orbits. A planet uses its gravity to snag bits of space stuff.
A planet’s gravity pulls equally from all sides. It pulls from the center to the edges. This makes the overall shape of a planet a sphere.
We all have seen and now we know why they are round or spherical but, are they all perfectly round? While all the planets are nice and round, some are more round than others. Mercury and Venus are the roundest of all. They are nearly perfect spheres. But others aren’t quite so perfectly spherical.
Jupiter and Saturn are thicker in the middle. As they spin, they begin to develop a rounded swelling that distorts their surface. This happens because when a planet spins, things on the outer edge have to move faster than things on the inside to keep up. This statement is valid for anything that can spin, like a wheel, a disc, or a fan.
Along the equator of a planet, gravity is holding the edges in but as it spins, stuff wants to spin out like mud flying off a tire. Saturn and Jupiter are really big and spinning really fast but gravity still manages to hold them together. That’s why they are swollen in the middle.
Saturn bulges most of all the planets in our solar system. If you compare the diameter from pole to pole to the diameter along the equator, it will not be the same.
Earth and Mars are small and don’t spin around as fast as Saturn and Jupiter, but they aren’t perfect spheres as well. They are more round than the giants.
Do you want to feel the forces from spinning?
First, make sure there are no obstacles around that you might bump into. Then either while standing, or in a spinner chair, spin around in circles. Hold your arms close to your body, then extend them out. Try moving your arms in and out and feel the difference. When your arms are stretched, your hands have to move faster than your shoulders to keep up, so you’ll feel more force on them.
Like that Elon Musk, Darklord!! You probably know already.
Originally published at https://www.prateekchaubey.com on March 2, 2021.