Blueshifting refers to the phenomenon of a celestial object moving towards the observer, resulting in a shift of its light towards the blue end of the spectrum. Synonyms for blueshifting include the Doppler effect, redshifting, and wavelength shifting. The Doppler effect occurs when waves (such as sound or light) are perceived differently depending on the motion of the observer and the source. Redshifting is the opposite effect of blueshifting, where an object moving away from the observer appears to have a longer wavelength, giving off a red shift. Wavelength shifting refers to the change in the frequency of light due to its interaction with a gravitational field or other phenomenon.