When a vibrating object is moving (toward, away from, alongside) an observer, the measured frequency of the vibrations will be lower than if the object is moving (toward, away from, alongside) an observer, the measured frequency of the vibrations will be higher than the actual rate of vibration of the object. When a star is moving towards an observer on earth, the light spectrum of the star will appear (redshifted, blueshifted, the same) compared to the light spectrum of the sun, which is considered to be in earth's frame of reference.