True anomaly

In astronomy, the true anomaly (, also written ) is the angle between the direction z-s of periapsis and the current position p of an object on its orbit, measured at the focus s of the ellipse (the point around which the object orbits). In the diagram below, true anomaly is the angle z-s-p.
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Noun
1. the angular distance of a point in an orbit past the point of periapsis measured in degrees
(hypernym) angular distance