angular displacement secular aberration The component of the stellar abberation resulting from the motion of the solar system in space. This component is usually ignored. The abberation is the apparent angular displacement of the observed position of a celestial object from its geometric position, caused by the finite velocity of light in combination with the motions of the observer and of the observed object. degree graad 度 microsecond (angle) microseconde (hoek) millisecond (angle) milliseconde (hoek)