Cosmology (Edexcel A Level Physics)

In 2016 astronomers announced the discovery of an Earth-like planet orbiting Proxima Centauri, the closest star to the Sun.

The planet was detected because of the small movement of the star as the planet orbited.
The movement was detected using the Doppler shift in the frequency of light travelling to the Earth.

The graph shows how the component of the star’s velocity v towards the Earth varied over time. 

Explain how the Doppler shift was used to obtain the data shown on the graph.

(3) 

Distance = .........................................