the light spectrum of the star will appear compared to the light spectrum of the sun, which is considered to be in Earth's frame of reference.

Answer 1

The light spectrum of a star will appear shifted towards the longer wavelength (redshifted) or shorter wavelength (blueshifted) end compared to the light spectrum of the sun. This shift occurs due to the Doppler effect, which describes how the motion of an object affects the observed frequency (or wavelength) of waves.

If a star is moving away from us, its light waves will be stretched, causing a redshift in its spectrum. This means that the wavelengths of the spectral lines emitted by the star will appear shifted towards the red end of the spectrum. On the other hand, if a star is moving towards us, its light waves will be compressed, leading to a blueshift, and the spectral lines will appear shifted towards the blue end of the spectrum.

This shift in the star's light spectrum is a result of the star's motion relative to the observer (Earth) and is independent of our frame of reference. The speed of light is constant, and its wavelength and frequency change only due to the relative motion between the source and the observer. Therefore, we can measure the redshift or blueshift of the star's spectrum relative to the spectrum of the sun, regardless of the frame of reference.