In the first step, equivalence of energy-time and momentum-position ph
ase spaces is discussed for simple periodic systems having a central f
orce. The discussion concerns the phase-space areas taken as a whole,
as well as their fragments. It is demonstrated that some fragments of
the phase space areas can fit together with a considerable accuracy. T
his suggests similar equivalence of the corresponding fragments of the
phase-space areas of the solar system. The hypothesis is examined in
respect to the planet orbits and the orbits of some planet satellites.