When an object's speed is high enough, its light does the same thing as sound. A galaxy moving toward the Earth would compress the light in front of it, which would make the wavelength of the light shorter. That means the light is shifted to the blue part of the spectrum, i.e., blueshifted. A galaxy moving away from the Earth would stretch the light behind it, which would make the wavelength of the light longer. That means the light is shifted to the red part of the spectrum, i.e., redshifted. The faster the object moves, the larger the effect. An object moving toward us appears blueshifted while one moving away from us appears redshifted. NASA A race car with a white headlight drives straight at you at over 200 mph. What color do you see the headlights?
A. White
B. Blue
C. Red