Aphs.219
net.space
utzoo!decvax!duke!phs!dennis
Sun Feb  7 10:51:10 1982
Re: sri-unix.707: Horseshoe Orbits
Nope -- it's not ignorance, it's just a point of view problem.  Higher
orbits are slower only in terms of angular velocity (speed relative to
the surface).  In linear velocity (yeah, orbits are ellipses, but
that's the idea) higher orbits are faster.  You need to accelerate from
a low orbit to achieve a higher one.  The ground speed is slower
because the circumference grows quickly wrt speed and it has more
distance to cover than it has extra speed to do it with.

Thus, the two moons exchange kinetic energy (orbital speed) via
gravitational attraction, and they BOTH (mutual and opposite) change
orbits.  The higher moon (the one caught up on) is decelerated and the
lower moon is accelerated, causing them to exchange orbits.  This will
collapse eventually (tidal forces ALWAYS eat some of that kinetic
energy), and either they will collide or just take up the same orbit;
I suspect collision.