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axis . C is the centre . The direction of
AB is the line of apses . The ratio of CS
to CA is the excentricity . The position of
the planet at A is the perihelion (nearest
to the sun). The position of the planet at
B is the aphelion (farthest from the sun).
The angle ASP is the anomaly when the
planet is at P. CA or a line drawn from S to
D is the mean distance of the planet from
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