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I understand that the sun exerts a force on the earth and that if that was the only force exerted on the earth then the earth would have already crashed into the sun a long time ago.

The reason the earth is not crashing into the sun but rather spins around it is because there is another force pushing the earth to go straight ahead (or something like that.. :D ). Now the combination of the sun pulling the earth towards it and that other force pushing the earth to keep moving forward results into this centrifugal force that makes the earth go round and round the sun instead.

Much like if I were ice skating and started moving forward really fast and as I was sliding forward I extended my right arm and grabbed hold of a metal pole standing there firmly I would all of a sudden start spinning round the pole. In that case, I am the earth, the pole is the sun, and the force that was pushing me forward and ended up making me go round in circles was generated by me pushing the ice behind me.

My question is, what is this other force in the case of the actual planet earth? Where does it come from and why isn't it fading away to the point where one day the earth will start spinning closer and closer into the sun until it crashes ?

Is it a vector of other forces (which ones) ?

As you can tell I'm just another physics enthusiast (but not a physicist nor a mathematician) asking the same questions over and over again so apologies in advance.


marked as duplicate by Aaron Stevens, Community Feb 16 at 22:58

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

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  • $\begingroup$ Thanks Thomas. So the answer is: "because almost all bodies in our solar system were formed from the same large clump of rotating gas and dust which due to conservation of angular momentum during its collapse both sped up and flattened into a disk, all of the solar system bodies (Earth, other planets, asteroids, etc), have enough forward velocity to continue orbiting the Sun without being pulled to the center." So now the question is where did that initial angular momentum come from.. but that's a different story.. $\endgroup$ – Sprout Coder Feb 16 at 22:57
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    $\begingroup$ Possible duplicate of Why doesn't the Moon fall onto the Earth? $\endgroup$ – Aaron Stevens Feb 16 at 22:58

There is no other (real) force. There only (real) force acting on the Earth is gravity, and it explains why the Earth is accelerating toward the Sun.

When an object moves in a circle, like the Earth approximately does, it is in fact accelerating toward the center even though it isn’t moving toward the center. This is because acceleration is the rate of change of the velocity vector, and the direction of this vector is changing in a radially inward direction.

Until you understand real forces like gravity and electromagnetic forces, and how they make objects accelerate, you should ignore everything you read about pseudo-forces like “centrifugal force”. They are not real forces due to interactions between particles. They are fake forces arising from using a “wrong” (i.e., non-inertial) coordinate system and they will do nothing but confuse you until you understand what an inertial reference frame is (which you don’t really need to do).


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