Opposition

Opposition is a term that describes the relative position of two heavenly bodies when Earth comes closest to being directly between them. At full moon, for example, the moon is in opposition to the sun. The term is most commonly used to describe positions with respect to the sun. When a superior planet—that is, one whose distance from the sun is greater than Earth’s—is on the opposite side of Earth from the sun, it is said to be in opposition. For example, the planet Mars is in opposition when Earth is directly between Mars and the sun.