3 ms·

thought you were going to say "moving towards us so quickly that their electromagnetic wavelengths are blueshifted"

• andyferris 4y ago
  That's right - I was definitely thinking of the twin paradox! (For those that don't know, the twin paradox is a theory of relativity thing - one twin travels out into space and back to Earth near the speed of light and afterward the stationary twin is older than the travelling twin, so the blue-shifted twin "lives longer" at least from Earth's point of view).