What does a blueshift in a distant galaxy's spectral lines indicate about its movement relative to the observer?

Answer

It is moving toward the observer.

A blueshift means the spectral lines have shifted to shorter wavelengths, which is the signature of relative motion toward the observer, as seen in the case of the Andromeda Galaxy.

What does a blueshift in a distant galaxy's spectral lines indicate about its movement relative to the observer?

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