If stars moving away/towards Earth appear blue/red shifted, how do we know their colours are red/blue because they are moving, and not just that they are a red/blue coloured star that’s relatively stationary?

Question

I copied the wording from a Quora post because all the answers were ELIhave a PHD in astrophysics.

In: 6

Answer 1

When we examine starlight we find it has a fingerprint that tells us the size, temperature and chemical makeup of the star. From that we can determine what color it should be. It is called astronomical spectroscopy.