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The Sun has a strong gravity. The planets also have gravity. So they attract each other. But then why dont they go and mix up with the Sun?

If it is the orbit of the planets or a pre-existing motion of a planet, then what is the reason behind this kind of motion? How did they happen to maintain the balance when there is no other force acting on the planets (except the sun)?

Lets say, somehow they had their motion from the very starting point. But now there is the gravity of sun acting on them, which means this pre-existing force will keep reducing until it vanishes. So after some time is passed, there would not be any balance in the solar system and thus they are supposed to fall down in the sun. But in reality that doesnt happen. So what is the reason and explanation?

Arafat
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1 Answers1

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The planets do fall towards the sun. Constantly. But they miss. Constantly.

  • Place a satellite high above the ground. It falls and crashes.

  • Now, throw it lightly sideways with a sideways speed. It falls and crashes but farther to the side.

  • Throw harder sideways so the sideways speed is greater. It crashes much farther to the side.

  • Now throw very, very hard so a very, very large sideways speed is achieved. It now "falls past" Earth! It falls but misses!

The satellite will now attain an elliptic orbit. Give it an even larger sideways speed, and the ellipsis flattens. At some sideways speed that is just right, the ellipsis becomes a perfect circle - you now have a circular orbit.

We observe the planets in our solar system to move in elliptic or close-to-circular orbits. They constantly fall towards the Sun, but they also constantly miss and "fall past" it. And this is how orbits can keep up for millions and billions of years.

Steeven
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