planetary aberration

planetary aberration

The apparent angular displacement of the observed position of a planet, etc., produced by motion of the observer (see aberration) and by motion of the observed body (see light-time).

Planetary Aberration


the aberration of light from a planet, comet, or other celestial body of the solar system, caused by the relative motion of the body and the earth. Planetary aberration consists of annual (stellar) aberration, which is a result of the earth’s motion around the sun, and the angular

Figure 1. (P) Position of celestial body, (o) position of observer

displacement of the body on the celestial sphere during the time it takes for light to travel from the body to the observer (the result of the body’s motion around the sun). It is defined as the angle between the body’s true direction at the moment when the observed light ray left the body and its true direction when the ray is observed on the earth. This definition is based on a theorem by Gauss, according to which the apparent direction to the body at time t coincides with the body’s true direction at time t — TAρ, where p is the body’s true distance from the observer (see Figure 1) and TA is the time it takes for light to travel 1 astronomical unit (light equation); TA = 0.005776 mean solar days.


Dubiago, A. D. Opredelenie orbit. Moscow-Leningrad, 1949.
Spravochnoe rukovodstvopo nebesnoi mekhanike i astrodinamike. Edited by G. N. Duboshin. Moscow, 1971.


planetary aberration

[′plan·ə‚ter·ē ‚ab·ə′rā·shən]
The apparent displacement of an object in the solar system that results from the fact that light takes a certain time to travel from the object to earth, during which time the object travels a certain distance in its orbit.