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?
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Geosynchronous satellites go very fast – about 3 km per second. However, they are also very far away from the Earth: about 36,000 km, which means (taking into account the Earth’s radius of 6,400 km) their orbit is a giant circle about 265,000 km in circumference.
That’s a really big circle. Even zooming along at 3 km a second, it takes 86,400 seconds to make it all the way around – that is 24 hours, or one day. That means by the time they make it all the way around, the Earth has also spun all the way around, and they are over the exact same point on the Earth where they started. In fact, they remained over that point the whole time, because the Earth rotated underneath them as they zoomed around the big circle.
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