A star has a spectrum shift exhibiting a red shift. What can you conclude about the distance from Earth to that star?
The distance is increasing.

The distance is decreasing.

The distance will remain unchanged.

The distance varies with the wavelength of the star.

Question

A star has a spectrum shift exhibiting a red shift. What can you conclude about the distance from Earth to that star? 
The distance is increasing. 

 The distance is decreasing. 

 The distance will remain unchanged. 

 The distance varies with the wavelength of the star.

jamesj · Answer

Red shift occurs when a star/galaxy is moving away from earth.  The light waves get 'spread out' by the movement of the star and become lower in frequency; that is they move towards the red end of the spectrum.  

This is just like the Doppler effect: I'm sure you've noticed that when an ambulance or fire truck goes by you the pitch of the siren goes down.