All Problems

Optics of Moving Sources

Problem 5.240

Aberration of light is the apparent displacement of stars attributable to the effect of the orbital motion of the Earth. The direction to a star in the ecliptic plane varies periodically, and the star performs apparent oscillations within an angle \(\delta \theta=41^{\prime \prime} .\) Find the orbital velocity of the Earth.

Reveal Answer
v=1/2cδθ=30 km/sv=1 / 2 c \delta \theta=30 \mathrm{~km} / \mathrm{s}