Blueshift is observed when

Question

A luminous object is stationary compared to a observer
A distant luminous object travels rapidly towards an observer
A distant luminous object travels rapidly away from an observer
A luminous object travels alongside an observer

Answer 1

Blueshift is observed when a distant luminous object travels rapidly towards an observer. This phenomenon occurs due to the Doppler effect, where the wavelength of light emitted by the object is compressed, resulting in a shift towards the blue end of the spectrum.