Aberration of light

Since heliocentricity, astronomers tried to see parallax in the stars as a result of the earth moving around the sun (186 million miles displacement). Rather than finding this parallax, Bradley ooked through a 212ft long telescope and found he had to tip the scope to catch the light as the earth moved, and unlocked a new way to calculate the speed of light.
 James Bradley England 1728 Aberration of light

Since heliocentricity, astronomers tried to see parallax in the stars as a result of the earth moving around the sun (186 million miles displacement). Rather than finding this parallax, Bradley ooked through a 212ft long telescope and found he had to tip the scope to catch the light as the earth moved, and unlocked a new way to calculate the speed of light.