3 ms·

Or would it be shifted to be more blue??

• marcodiego 6y ago
  Only if it was getting closer.
  • AnimalMuppet 6y ago
    It's the reply from the machine to you. It should be blue.
    • cgriswald 6y ago
      The message is always heading in the same direction. The relevant variable is the movement between the machine and you. You should probably hope it’s red because if the machine is fast enough that the blue shift is perceivable to the human eye, it might be the last thing you see.