Answer:
The spectrum will shift to the red.
Explanation:
This phenomenon is called as 'Doppler effect'. Doppler effect occurs when a source of waves moves relative to an observer: when this happens, the wavelength of the observed wave appears shifted to the observer.
In this situation, the source of the waves is the star, which emits light (the waves). The observer is on Earth, and the star (the source of the waves) is moving away from the observer: therefore, the wavelength of the light observed by us is shifted with respect to the original wavelength of the light emitted by the star.
In particular, we have two different situations:
- when the star moves away, the wavelength increases, so it shift towards the red (which corresponds to light with longer wavelength) - this effect is called red-shift
- when the star moves towards us, the wavelenght decreases, so it shift towards the blue (which corresponds to light with shorter wavelength) - this effect is called blue-shift
In this situation, the star is moving away from us, so the correct choice is
The spectrum will shift to the red.
