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parallactic displacement




The apparent change in a star's position caused by the movement of Earth in its orbit; also known as parallactic motion. Over the course of a year, a star appears to follow a small path in the sky called a parallactic ellipse, or a parallactic orbit, the shape of which ranges from a circle for a star at the ecliptic pole to a line for a star on the ecliptic.


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   • CELESTIAL MECHANICS