What are Red Shifts Characteristics?

Answer 1

"Red shift" is what we call the "away" version of the Doppler Effect; the "towards" version is called "blue shift." With visible light, things that are retreated at high speed look as though they were colored more toward the long end of the spectrum than they really are. Since the longest color we can see is red, we call this redshifting, although the actual color change we see might be from blue to green (blue is the shortest light we can see -- counting indigo, violet and purple as "blues" --and green is in the middle, so we see it best). The Doppler Effect is also the thing that makes a siren seem to change pitch as it approaches, passes and then leaves your position, something like "iiiiiieieeieeeieeeeeeoeooeooooo oo oo ooo oooo". Since we don't see sound, we don't generally use color words to describe it, but that "iiiiii" portion is the blue shift, the "eeeeee" is the regular siren sound, and the oooo o o o oo oooo" is the redshift.