Measurement of the approach velocity of the Andromeda Galaxy (M31)
from its blue Doppler shift

Wavelength scale calibrated from nearby star Beta Arietis

Image used by Prof. Jim Al-Khalili in the program "Secrets of Size: Atoms to Supergalaxies"
Episode 2, BBC 4, 23rd May 2022, 9:00pm

Details on Image
2021-12-06 @ 21:48 UT