= James Bradley
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<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>.<A New Discovered Motion of the Fixed Stars by James Bradley>[Original letter to Edmond Halley: annual stellar displacements and finite-speed explanation]{ref}
\Image[https://upload.wikimedia.org/wikipedia/commons/9/9f/James_Bradley.jpg]
{title=Portrait of <James Bradley>}
{description=Public-domain historical engraving, hosted by Wikimedia Commons.}
{source=https://commons.wikimedia.org/wiki/File:James_Bradley.jpg}
{width=260}
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