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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Separate the two movements and it makes it easier to visualize.
If you put a yardstick on a basketball that would represent the forward motion of a satellite. You can see how eventual that forward motion would mean it would shoot off somewhere into space never to be seen again. So there has to be a downward motion around to wrap around the basketball. For example two units forwards and one unit down.
In a satellite it’s the downward is what we call falling. In a geosynchronous orbit the motion forward and the motion down is the same. So on earth it appears to be in the same spot because the earth is also rotating
Separate the two movements and it makes it easier to visualize.
If you put a yardstick on a basketball that would represent the forward motion of a satellite. You can see how eventual that forward motion would mean it would shoot off somewhere into space never to be seen again. So there has to be a downward motion around to wrap around the basketball. For example two units forwards and one unit down.
In a satellite it’s the downward is what we call falling. In a geosynchronous orbit the motion forward and the motion down is the same. So on earth it appears to be in the same spot because the earth is also rotating
They fall at the right distance away around the earth that their velocity matches that of the spot on the earth as it rotates. Or another way of thinking about it is that the orbital period is 24 hours around the axis the earth spins. You cannot have geosynchronous orbit by orbiting the poles north south, the farther you deviate from the rotation of the earth the less synchronous it becomes.
They fall at the right distance away around the earth that their velocity matches that of the spot on the earth as it rotates. Or another way of thinking about it is that the orbital period is 24 hours around the axis the earth spins. You cannot have geosynchronous orbit by orbiting the poles north south, the farther you deviate from the rotation of the earth the less synchronous it becomes.
> The trick to flying is to throw yourself at the ground and miss
Orbits can be very counter-initiative. The faster you go, the higher you reach. However, due to complicated physics interactions, a higher orbit is faster through space but slower relative to the body’s surface. You accelerate to move slower. This relationship enables a geosynchronous orbit altitude where your orbital period matches the rotation of the body you are orbiting. While you are moving faster through space than low orbit, your speed relative to the body’s surface is basically zero.
Note that geostationary orbit is actually just one specific ring at geosynchronous altitude. If you aren’t on this specific ring right above the equator and running west to east, referred to as 0 degrees of inclination, you will be seen to be swinging north and south from the surface like an inverted pendulum, And if your orbit is not completely at the specific geosynchronous altitude, you could be seen as moving in a figure-8 pattern from the surface, like a solar analemma repeating every orbit.
> The trick to flying is to throw yourself at the ground and miss
Orbits can be very counter-initiative. The faster you go, the higher you reach. However, due to complicated physics interactions, a higher orbit is faster through space but slower relative to the body’s surface. You accelerate to move slower. This relationship enables a geosynchronous orbit altitude where your orbital period matches the rotation of the body you are orbiting. While you are moving faster through space than low orbit, your speed relative to the body’s surface is basically zero.
Note that geostationary orbit is actually just one specific ring at geosynchronous altitude. If you aren’t on this specific ring right above the equator and running west to east, referred to as 0 degrees of inclination, you will be seen to be swinging north and south from the surface like an inverted pendulum, And if your orbit is not completely at the specific geosynchronous altitude, you could be seen as moving in a figure-8 pattern from the surface, like a solar analemma repeating every orbit.
> The trick to flying is to throw yourself at the ground and miss
Orbits can be very counter-initiative. The faster you go, the higher you reach. However, due to complicated physics interactions, a higher orbit is faster through space but slower relative to the body’s surface. You accelerate to move slower. This relationship enables a geosynchronous orbit altitude where your orbital period matches the rotation of the body you are orbiting. While you are moving faster through space than low orbit, your speed relative to the body’s surface is basically zero.
Note that geostationary orbit is actually just one specific ring at geosynchronous altitude. If you aren’t on this specific ring right above the equator and running west to east, referred to as 0 degrees of inclination, you will be seen to be swinging north and south from the surface like an inverted pendulum, And if your orbit is not completely at the specific geosynchronous altitude, you could be seen as moving in a figure-8 pattern from the surface, like a solar analemma repeating every orbit.
Imagine a yoyo. Now instead of yoyoing, you twirl it above your head like a lasso. The yoyo is the satellite, the string represents gravity, and your finger is Earth. Now if you do the same with a shorter string, the yoyo spins faster. If you were to make the string longer, the yoyo spins slower. Same thing happens with satellites. Those in lower orbits, closer to Earth, orbit quickly. Those further out orbit slower. Geosynchronous orbit is the orbit where a satellite takes exactly one sidereal day to spin around once, and a geostationary orbit is a geosynchronous orbit aligned with the equator. Now because Earth revolves once on its axis in a sidereal day, it and the satellite appear to stay in a straight line even though they’re actually spinning around. If you go above a geosynchronous orbit, the satellite actually appears to move backwards!
Imagine a yoyo. Now instead of yoyoing, you twirl it above your head like a lasso. The yoyo is the satellite, the string represents gravity, and your finger is Earth. Now if you do the same with a shorter string, the yoyo spins faster. If you were to make the string longer, the yoyo spins slower. Same thing happens with satellites. Those in lower orbits, closer to Earth, orbit quickly. Those further out orbit slower. Geosynchronous orbit is the orbit where a satellite takes exactly one sidereal day to spin around once, and a geostationary orbit is a geosynchronous orbit aligned with the equator. Now because Earth revolves once on its axis in a sidereal day, it and the satellite appear to stay in a straight line even though they’re actually spinning around. If you go above a geosynchronous orbit, the satellite actually appears to move backwards!
Imagine a yoyo. Now instead of yoyoing, you twirl it above your head like a lasso. The yoyo is the satellite, the string represents gravity, and your finger is Earth. Now if you do the same with a shorter string, the yoyo spins faster. If you were to make the string longer, the yoyo spins slower. Same thing happens with satellites. Those in lower orbits, closer to Earth, orbit quickly. Those further out orbit slower. Geosynchronous orbit is the orbit where a satellite takes exactly one sidereal day to spin around once, and a geostationary orbit is a geosynchronous orbit aligned with the equator. Now because Earth revolves once on its axis in a sidereal day, it and the satellite appear to stay in a straight line even though they’re actually spinning around. If you go above a geosynchronous orbit, the satellite actually appears to move backwards!
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