if you wait long enough for the universe to expand before you measure it. That is the so-called red shift. But if you are reasonably close to the source, certainly if within our solar system, then the wavelenght of a narrow spectral line is fixed.
BTW, both the wavelength and the frequency change since the speed of light remains constant.

Thanks for the plaudit, but it seems to me that Alexander is a more knowledgeable physicist than I. He seems to know the standard explanation of most things. But to be interested in power gliding, skiing etc., he must still be fairly young- like in his forties or fifties- that's young in my mind.