Final answer:
Spectral lines shifted towards the red end of the spectrum illustrate that the star is moving away from us, due to the Doppler effect. This redshift helps astronomers determine the radial velocity and the speed of the receding star.
Step-by-step explanation:
When the observed spectral lines of a star are all shifted towards the red end of the spectrum, it indicates that the star is moving away from us. This phenomenon is a result of the Doppler effect, which describes the changes in frequency or wavelength of a wave in relation to an observer who is moving relative to the wave source. If the lines were shifted towards the blue end, it would mean the star is moving towards us. However, when all spectral lines are shifted to the red, it signifies a redshift, confirming that the star's radial velocity is away from the observer.
The shifting of spectral lines serves as a critical tool for astronomers to measure the movement of stars and galaxies in the universe. Such measurements are essential to study the motion, composition, and distribution of celestial objects. By analyzing the degree of redshift, astronomers can even gauge the speed at which stars or galaxies are receding.