 James Bradley

James Bradley discovered aberration of light while making precise repeated measurements of stellar directions. The annual displacement did not have the timing expected for stellar parallax. He explained it by combining the observer's orbital velocity with the finite speed of light.

For a transverse observer speed $v\ll c$, the characteristic aberration angle is about $v/c$ in radians. Its dependence on the observer's velocity, rather than the star's Euclidean distance, distinguishes it from parallax. The effect supplied evidence for the orbital motion of Earth and a way to relate terrestrial orbital speed to the speed of light.^[ref]

James Bradley can refer to various individuals and contexts, depending on the field or subject matter. Some notable references include: 1. **James Bradley (Author)**: An American author known for his books on history, particularly "Flags of Our Fathers," which tells the story of the soldiers who raised the American flag at Iwo Jima during World War II. He also wrote "Flyboys," which recounts the experiences of American pilots during the war.