originally posted by: Out6of9Balance
a reply to: Soylent Green Is People
shouldn't the satellites fall down according your theory?
No. Satellites are in orbit moving sideways at a speed that is fast enough relative to their height so that while they are being pulled back to
Earth, the Earth "curves away" under itself, so the falling (i.e., orbiting) satellite "misses" the ground.
That's what an orbit is. Like I said, things in orbit do not experience a lack of earth's gravitational pull, but are in orbit because of Earth's
A good way to illustrate how the surface of the Earth curves away from an orbiting spacecraft before the spacecraft can hit that surface is the
following thought experiment Isaac Newton proposed back in 1687 that has become known as "Newton's Cannonball".
In this graphic representation of the thought experiment, cannonball A with the least velocity quickly falls back to earth due to gravity. Cannonball
B has a bit more velocity that allows it to go almost to the edge of the curve, but not quite. Both A and B hit the ground because the ground "gets
in their way" (so-to-speak).
Cannonball C, which has a greater velocity than both A and B, also gets pulled back down, but because of that greater velocity it can goes further out
over the curved surface.
In fact, cannonball C so far out over the curved surface of the Earth that as gravity pulls it back down the surface curves away allowing cannon ball
C to miss the ground.
Now, instead of cannonballs, imagine these are satellites moving "sideways" to the ground at orbital speeds.
By the way, even a geostationary satellite is moving at a sideways speed realtive to Earth's surface, but that speed matches the rotational speed of
Earth, so the satellite remain over the same spot on Earth as Earth turns.
This link has a good "quickie" explanation (excerpted below): www.astronautix.com...
This was the first and best explanation of what an orbit is. An object in orbit is weightless not because 'it is beyond the earth's gravity' but
because it is in 'free-fall' - just like a skydiver. The difference is that it has enough horizontal speed never to hit the ground.
edit on 12/12/2018 by Soylent Green Is People because: (no reason given)