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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Objects in Geosynchronous orbit are *still falling*, they’re just falling at the *same speed as the earth is rotating*.
Since the earth can more or less be thought of as a sphere, therefore the effect it has on gravity is still a sphere, no matter which way it’s facing. In the same way that driving on the outside of a turn on a racetrack is slower than driving on the inside, the further away you are from earth the easier it is to continuously “miss,” the earth as you fall, allowing it to keep pace with the speed the earth is spinning.
Because that point is not stationary. The world turns. So the satellite is in an orbit, spinning around the earth, just like anything else in orbit. And yes, that means it’s constantly falling past the earth. The fact that the earth is turning is irrelevant to the orbit, the earth could start turning ten times as fast or stop turning completely. It doesn’t affect the orbit of the satellite.
They are going JUST the right speed, in the same direction as the planet’s rotation is going.
Objects in Geosynchronous orbit are *still falling*, they’re just falling at the *same speed as the earth is rotating*.
Since the earth can more or less be thought of as a sphere, therefore the effect it has on gravity is still a sphere, no matter which way it’s facing. In the same way that driving on the outside of a turn on a racetrack is slower than driving on the inside, the further away you are from earth the easier it is to continuously “miss,” the earth as you fall, allowing it to keep pace with the speed the earth is spinning.
They are going JUST the right speed, in the same direction as the planet’s rotation is going.
Geosynchronous orbit only means the orbital velocity will match the rotational velocity of the earth.
Orbits get slower the higher you go, so objects in geosync (37000km) go much slower than those at 400km. Go higher, and the speed relative to the Earth is lower. Someone standing on earth would notice the satellite to moving in reverse, eventhough it isn’t.
Things in low orbit zip around the planet every 90 minutes or so. The moon, on the other hand, is in a very high orbit, and takes almost a month to orbit the earth. Somewhere in between, there is a circular orbit whose period is exactly 24 hours – it orbits around the earth at the same rate the planet spins. This is called a geosynchronous orbit. If it’s above the equator, there is no north/south drift, so the satellite stays above one spot on the surface – this is a geostationary orbit.
Because that point is not stationary. The world turns. So the satellite is in an orbit, spinning around the earth, just like anything else in orbit. And yes, that means it’s constantly falling past the earth. The fact that the earth is turning is irrelevant to the orbit, the earth could start turning ten times as fast or stop turning completely. It doesn’t affect the orbit of the satellite.
Because that point is not stationary. The world turns. So the satellite is in an orbit, spinning around the earth, just like anything else in orbit. And yes, that means it’s constantly falling past the earth. The fact that the earth is turning is irrelevant to the orbit, the earth could start turning ten times as fast or stop turning completely. It doesn’t affect the orbit of the satellite.
Things in low orbit zip around the planet every 90 minutes or so. The moon, on the other hand, is in a very high orbit, and takes almost a month to orbit the earth. Somewhere in between, there is a circular orbit whose period is exactly 24 hours – it orbits around the earth at the same rate the planet spins. This is called a geosynchronous orbit. If it’s above the equator, there is no north/south drift, so the satellite stays above one spot on the surface – this is a geostationary orbit.
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