Red-shift

EMISSION SPECTRA: Light from a star doesn't contain all wavelengths of the EM spectrum as elements in the star absorb some of the emitted wavelengths (so dark lines are present when the spectrum's analysed). Different elements produce different patterns of dark lines. SPECTRA FROM DISTANT GALAXIES: When astronomers observe light from distant galaxies, they can see it is different to the light from the sun. The dark lines in the spectra from distant galaxies show an increase in wavelength. The lines are moved or shifted towards the red end of the spectrum - Red-Shift RED-SHIFT & SPEED: Astronomers see red-shift in virtually all galaxies, its a result of the space between the Earth and the galaxies expanding. This expansion stretches out the light waves during their journey to us. shifting them towards the red end of the spectrum. The more red-shifted the light from a galaxy is, the faster the galaxy is moving away from Earth