Movie 11 (0:49)

Script : Returning to the tram we now consider the colour shift. Even at low speeds, ten percent of the speed of light, objects change their colour significantly. Lamp posts ahead look green, but behind they look red.

This is the Doppler shift at work.
Just as the direction of motion of photons change when the camera moves, so do the frequencies which we perceive as colour. Objects we move towards appear blueshifted. Objects we move away from appear redshifted. As we go faster, the effect becomes extreme, and we see a rainbow effect as any sharp spectral features pass through the visible band.

This is the cause of red-shift, an observation astronomers made which showed nearly all stars in the universe are moving away from us and each other.