Aberration of starlight
The apparent displacement of a star from its real position on the celestial sphere caused by the motion of the Earth in its orbit around the Sun. Aberration was discovered, in the late 1720s, by James Bradley when he was trying to measure parallax . The displacements of the stars were much greater than were expected from the parallax phenomenon. Angular changes of up to 20 arcseconds in the positions of the stars were measured and these are much larger than those due to parallax: Alpha Centauri , the nearest star, has the greatest parallax but even that is only 0.76 arcseconds. The measurements were finally explained by considering the fact that light has a finite velocity and the Earth is in constant motion. In the time it takes light to travel into our eye, our vantage point has moved and its velocity is superimposed upon that of the light from the star. Since our minds extrapolate light sources in a straight line, we appear to see the star in a direction that is slightly displaced from its true position. | ||||
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Aberration of light
The aberration of light (also referred to as astronomical aberration or stellar aberration) is an astronomical phenomenon which produces an apparent motion of celestial objects. It was discovered and later explained by the third Astronomer Royal, James Bradley, in 1725, who attributed it to the finite speed of light and the motion of Earth in its orbit around the Sun.
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