Motion

All planets in the Solar System revolve around the Sun in a counterclockwise direction when one views them from the north pole of the celestial sphere (Figure 1). They all lie close to a plane known as the ecliptic plane.

From the Earth¡¦s perspective, the planets are observed to move closely along a circle known as the ecliptic - the apparent path of the Sun¡¦s movement on the celestial sphere as seen from the Earth. The rise and set of a planet as observed from the Earth is related to its apparent motion relative to the Sun. This apparent motion depends on whether the planet is nearer the Sun than the Earth (an inferior planet) or further away from the Sun than the Earth (a superior planet).
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