aberriation

Aberration, in a general sense, refers to a departure from what is normal, true, or expected. This deviation can manifest in various fields, each with its specific definition and context. In optics, an aberration is a flaw in a lens or mirror that prevents light from focusing at a single point. Common optical aberrations include spherical aberration, where light rays passing through the edges of a lens are focused at a different point than rays passing through the center, and chromatic aberration, where different colors of light are refracted at different angles, leading to color fringing.

In astronomy, an aberration of starlight is an optical phenomenon caused by the finite speed of light and the motion of the observer. It results in the apparent position of a star being slightly shifted from its true position. This effect is analogous to how rain appears to fall at an angle when one is walking through it, even if it is falling vertically. There are two main types: annual aberration, caused by the Earth's orbit around the sun, and diurnal aberration, caused by the Earth's rotation.

More broadly, the term aberration can also describe a deviation from moral or intellectual soundness, such as a delusion or a departure from common sense. This usage implies a departure from what is considered rational or proper behavior or thinking. Therefore, while the core concept of aberration is a deviation, its specific meaning is heavily dependent on the context in which it is used, whether it be in the realm of physics, astronomy, or general human behavior.