In the Shifting Light Spectra activity, as the galaxy moves away from the blue planet, its spectrum will exhibit a redshift. This means that the wavelengths of light emitted by the galaxy's stars and elements will stretch, resulting in a shift toward the red end of the spectrum. You may observe that the lines in the spectrum that correspond to specific elements will move to longer wavelengths.
Conversely, when the galaxy moves toward the blue planet, its spectrum shows a blueshift. In this case, the wavelengths of light are compressed, causing a shift toward the blue end of the spectrum. The spectral lines associated with elements will appear to move to shorter wavelengths.
Overall, the movement of the galaxy relative to the blue planet results in a clear visual change in the spectral lines depending on whether it is approaching or receding. This phenomenon is a critical aspect of understanding cosmic motion and redshift/blueshift in astronomy.