On Apr 29, 7:20 pm, Jeff$B"%(BRelf wrote:
Oops, I meant to write $B!H(B faster $B!I(B, not $B!H(B higher $B!I(B:
$B!H(B If the earth's orbit around the sun happened to be slightly faster
it'd be Spiraling Away From the sun ( a bit more each year );
conversely, it'd be spiraling Into the sun. $B!I(B.

Okay, the statement is now clear. Now, I can definitely say it is
wrong, which I couldn't honestly say before. If the earths orbit
happened to be slightly faster it would go into another orbit which on
average would be farther from the sun. This orbit would be just as
stable as the orbit is right now. Newton's Law of mechanics have been
used for hundreds of years to calculate orbits.
Two body orbits are quite stable (i.e., earth, sun, and nothing
else). A body can't entirely leave orbit without reaching an escape
velocity. Unless the orbital velocity is very close to the escape
velocity, a small perturbation would result in a small change in
orbit.The earth orbital velocity is no where near the escape velocity
needed to escape from the sun. The fancy way to say it: The earths
orbit is robust against small perturbations.
There are complications with three or more bodies. They are not
always stable over long time frames even without a perturbation.
However, those orbits that are stable will not be destroyed by an
small perturbation.
The orbit slowly increases due to the tides and frictional
forces. As I stated before, gravitational forces alone can't destroy a
two body orbit. Tidal forces are gravitational forces. However,
frictional forces plus gravitational forces can eventually increase
orbital distance.The deformation of the earth by lunar tides generates
a lot of friction. It takes hundreds of millions of years to make a
difference, however.