Collier's New Encyclopedia (1921)/Aberration

ABERRATION, a wandering from.

In optics, a spherical aberration is that wandering of the rays of light from the normal path which takes place when they are made to pass through curved lenses, or are reflected from curved mirrors, constituting portions of a sphere, instead of parts of a parabola. Chromatic aberrations is the fringing of images with the prismatic colors which takes place when light passes through curved lenses.

In astronomy, the aberration of light is that alteration in the apparent position of a star which is produced by the motion of the earth in its orbit during the time that the light is coming from the star to the eye. The effect of this aberration is to make each star appear annually to describe a minute circle of about 40' diameter parallel to the earth's diameter.

In medicine, the passage of blood, or any other fluid of the body, from morbid causes, into vessels not designed to receive it. Mental aberration is that wandering from soundness of judgment which is so conspicuous in the insane.