Red shift is when light waves are stretched out as if the star/galaxy is moving away from us.
This is because the spectrum of light is shifted towards the red part of the spectrum.
Blue shift is when the light waves are squashed together if the star/galaxy is moving towards us.
This is because the spectrum of light is shifted towards the blue part of the spectrum.
The faster a star or galaxy is moving towards/away from, the bigger the shift is.
Red and Blue shifts are examples of the Doppler Effect.
The Doppler Effect is:
- The change in the observed wavelength and frequency of waves due to the motion of the source towards/away from the observer.
- Christian Doppler discovered the effect in 1842 using sound waves.
- He demonstrated it by sending an open railway carriage filled with trumpeters speeding past a line of listeners.
- Light from distant galaxies are red shifted.
- The further a galaxy is from us, the bigger its red shift.
- The distant galaxies are moving away from us.
- The speed of reccesion of a…