Natural Science Forum / Physics / General Physics / July 2008

No force is necessary to cause orbital motion.
The planets orbit the sun (( roughly the center of
the effective mass (M-m) of the rest of the
universe ))  at a special mean orbital radius to
conserve total energy.

SEE BOOK:
ONE WITH THE UNIVERSE-
           THE MECHANICS OF
           THE UNIVERSE
           by  Allen C. Goodrich

SEE: ISBN  0-595-41598-9

THE MECHANICS OF
THE UNIVERSE

Copyright 1984-2007  Allen C. Goodrich

Orbital motion has nothing to do with a force of
gravity. Obrital motion obeys the first law of
thermodynamics, which says that the total
energy of the universe is a constant.
Orbiting masses have kinetic and potential
energies that are nearly equal, because
this occurs at the only orbital radius where
a positive change of kinetic energy is
accompanied by a negative change of
potential energy, complying with the first
law of thermodynamics. .
All of the planets and moons orbit in a
manner that is consistent with the first law
of thermodynamics..
Any orbiting mass, m, such as the earth,
has a kinetic energy  m (2 pi L )^2 / t^2
because of its velocity ,v , as  m v^2 , and
a potential energy  G ( M-m ) m  / L,
because of its orbital radius L and the product
of the mases m and the rest of  the effective
mass of the universe M-m, where M is the
effective mass of the total universe.  In the
solar system this mass M would effectively
be the sum of the masses of the sun and
the rest of the masses of the planets and
moons of the solar system.
The sum of kinetic and potential energies
would be a constant for any particular planet,
or moon , because , no force,  as a  source
of an energy change, is available to the
orbiting mass ( if it is not in
contact with another mass ) . So,  it continues
to orbit at nearly the same  radial distance from
the center of the mass of the rest of the
effective universe, complying with the first law
of thermodynamics, as the fundamental
equation of the universe.