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retrograde motion




Rotation or orbital motion in a clockwise direction when viewed from above the north pole of the primary (i.e., in the opposite sense to most satellites); the opposite of direct motion. The north pole is the one on the same side of the ecliptic as Earth's north pole. For example, Venus displays retrograde axial rotation and the outer four moons of Jupiter display retrograde orbital rotation.

The term is also applied to the apparent backward (i.e., westward) motion of a planet due to the Earth's own motion.


Related category

   • CELESTIAL MECHANICS