Light travels at the same speed in all directions and its speed does not depend on either the speed of the source or on that of the observer. The Doppler-effect can be observed during the propagation of light as well, but due to the propagation behaviour of light there is no difference between the two movement types.

Studying the spectrum of the stars in the universe no new spectrum has been found, their structure is similar to the spectrum of the materials which can be found on Earth, but the frequency of the colours was lower. The colours were shifted towards the red colour and this phenomenon is called “cosmological red-shift”.

Accordingly, this means that due to the Doppler-effect the stars are moving farther from one another.

The lined spectrum of the fixed material

The lined spectrum of the moving off star's material