  Based on Maxwellian quaternionic electromagnetic theory, the electromagnetic
interaction, gravitational interaction and their coupling influence with the
dark matter field in octonionic space are discussed. The research results
disclose the close relationships of dark matter field with electromagnetic and
gravitational interactions. In the electromagnetic interaction, the variation
of field energy density has direct effect on the force of charge and current.
In the modified gravitational interaction, the near coplanarity, near
circularity and corevolving of planetary orbits are deduced from the equations
set. The change of centrifugal force of celestial body leads to fluctuation of
revolution speed, when the field energy density, celestial body's angular
momentum in its sense of revolution or its mass spatial distribution varied. In
the dark matter field, the equations set reveal the movement properties of dark
matter in certain conditions and its influence on ordinary matter movements.
The research results explain that some observed abnormal phenomena about
celestial bodies are caused by either modified gravitational interaction or
dark matter.
