The View from a Fast Ship

Relativistic Doppler shift and aberration

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Approaching at $\beta c$: frequencies multiply by $\sqrt{\frac{1+\beta}{1-\beta}}$.
• Aberration crowds the view toward the direction of travel.
• The CMB dipole reveals our motion through the universe at about 370 km/s.

Steps

1. Light from a moving source
2. Red becomes ultraviolet
3. Starbow
4. A sideways star
5. Our motion through the cosmos
6. Red light, green light