eli5: I’ve heard orbit described as continuously falling past or missing the Earth, how then do objects in geosynchronous orbit above a single point not fall out of the sky?

Question

eli5: I’ve heard orbit described as continuously falling past or missing the Earth, how then do objects in geosynchronous orbit above a single point not fall out of the sky?

In: 2204

Answer 1

Suppose a satellite is in orbit (non geosynchronous). Then imagine that the rotation of the earth magically changes so that it is spinning at the same speed the object is orbiting. That wouldn’t affect the orbit of the satellite at all, except that you can now call its orbit “geosynchronous”. This shows that geosynchronous orbit is really just a coincidence between a particular orbit, and a particular rotational speed of the earth.

The only case in which that would be a problem would be if the earth wasn’t spinning at all. Then a “geosynchronous” satellite *would* fall out of the sky.