-- The speed of the orbiting body is the same at every point in its orbit.
-- Since a circle is the ellipse with coincident foci, the central body is
at the center of the circular orbit.
-- The radius of the circular orbit drawn from the central body to the
orbiting body sweeps out the same amount of area in every same
amount of time.
-- The forces of attraction between the central body and the orbiting body
may be electrostatic, magnetic, or gravitational.
-- The circular orbit never occurs in nature. In the case of TV satellites
that appear 'fixed' in the sky, their orbits must constantly be adjusted to
maintain circularity and prevent them from drifting off station..
