• Position of a planet opposite the Sun in the sky as seen from Earth. A planet at opposition is at its closest approach to the Earth and is visible all night, making opposition the ideal time for observation of the superior planets.
  • The resistance something offers to something else. For example, the opposition a given material offers to the flow of current or to the passage of magnetic flux.
  • The circumstance or state where two periodic quantities having the same frequency and waveshape are out-of-phase by 180°. Also called phase opposition.

Not what you were looking for?