science · 13 July 1762 · 262 years ago
death
Died 13 Jul 1762 (born Mar 1693).
English astronomer who was the third Astronomer Royal. He discovered the aberration of starlight (announced 1728). This apparent slight change in the positions of stars results from the position change of the observer on the Earth, as it revolves around the sun. Bradley thus established the first direct evidence of the revolution of the Earth around the Sun. He was a skilled astronomer who took great pains to enable accuracy in all his measurements. The aberration of starlight showed that light had a finite speed, which he calculated to be about 283,000 km/s. Bradley also discovered an annual change in the declination in some of the fixed stars, deducing that the earth nods a little on its axis of rotation (which he named as nutation) due to the gravitational pull of the Moon.
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