James Bradley

Chronicled events

1. 1729​·​Starlight Tilts with the Earth’s Motion
   #5813

   Gamma Draconis, and the other stars I’ve measured, shift back and forth over the year by about 20 seconds of arc, always toward the direction the Earth is moving in at the time. Light takes time to arrive, and the Earth’s motion slants the direction it seems to come from. A motionless Earth can’t produce this.