Aberration of light

Aberration of light (also referred to as astronomical aberration or stellar aberration) is an astronomical phenomenon defined as an apparent motion of the heavenly bodies; stars describing more or less elliptic annual orbits, according to the latitude of the star; consequently at any moment the star appears to be displaced from its true position. This apparent motion is due to the finite speed of light relative to the velocity of an observer on the Earth. It has three components: diurnal aberration, annual aberration, and secular aberration. Secular aberration is due to the motion of the Sun through space, whose rectilinear motion when combined with a star's rectilinear motion cannot be distinguished from the deflection due to light-time and is thus ignored. Diurnal aberration is due to Earth's rotation on its axis and does not exceed 0.32" (it is most pronounced for equatorial observers). The rest of this article concerns annual aberration due to the velocity of the Earth in its annual orbit about the Sun.

Related Topics:
Apparent motion - Star - Elliptic - Orbit - Latitude - Speed of light - Earth - Sun

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