When describing the positions of the planets with respect to the earth, there are several terms that are commonly used. When a planet is in the same direction in the sky as the sun, it is said to be in conjunction . Conjunction is the worst time to try to see a planet in the sky. For the planets Mercury and Venus, there are two possible conjunctions. Inferior conjunction occurs when the planet passes between the earth and sun.
Superior conjunction occurs when the planet passes on the far side of the sun.
The terms inferior and superior refer only to the relative distance from the earth. For the rest of the planets, there can only be one conjunction on the far side of the sun. These planets can never pass between the earth and sun. The term opposition is used to describe the condition when the planet is opposite the sun in the sky as seen from the earth. When a planet is in opposition, it rises when the sun sets and sets when the sun rises.