In the ancient astronomy the anomaly was taken as the angular distance of the planet from the point of the farthest recession from the earth.
The angle from the pericentre to the actual radius vector, and the length of the latter being found, the angular distance of the planet from the node in the plane of the orbit is found by adding to the true anomaly the distance from the node to the pericentre.
A fifth element is the position of the pericentre, which may be expressed by its angular distance XFN from the ascending node.
Regarded as a linear velocity, the parallactic motion is the same for all stars, being exactly equal and opposite to the solar motion; but its amount, as measured by the corresponding angular displacement of the star, is inversely proportional to the distance of the star from the earth, and foreshortening causes it to vary as the sine of the angular distance from the apex.
It should be noticed that clocks, on which Tycho Brahe depended very little, were used at Cassel for finding the difference of right ascension between Venus and the sun before sunset; Tycho preferred observing the angular distance between the sun and Venus when the latter was visible in the daytime.
In astronomy the word denotes the angular distance of a body from the pericentre of the orbit in which it is moving.
This angle, therefore, divided by the magnifying power of the telescope gives the real angular distance of the centres of a double star.
AZIMUTH (from the Arabic), in astronomy, the angular distance from the north or south point of the horizon to the foot of the vertical circle through a heavenly body.
Amplus, large), in astronomy, the angular distance of the rising or setting sun, or other heavenly body, from the east or west point of the horizon; used mostly by navigators in finding the variation of the compass by the setting sun.