The Enigma Of The Universe ► 2 ►Universe In Modern Science ► (A) How Big Is The Universe? ► 3. The Expanding Universe ► Red-shift in Spectra

Posted: 10.10.2014

The actual phenomenon which was observed was that when the spectra of the light coming from distant galaxies were studied with a spectrometer, it was noticed that the spectral lines are shifted slightly towards the red end of the spectrum.[1] This happens due to what is generally known as ‘Doppler Effect’[2] according to which the light coming from a source that is approaching the observer changes its colour towards the violet end of the spectrum and light from a receding source changes towards the red. Thus, if the galaxies were really receding away from the earth, their light would appear more red. The spectroscopic analysis actually showed a definite shift towards the red end of the spectrum, and hence, it was established that the galaxies were receding from one another, i.e., there is the general uniform expansion of the system of galaxies scattered through the space of the universe.

Footnotes:
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