Geocentric Science

The Doppler Effect is a change in pitch (frequency) due to an object’s motion – the wavelength changes causing the pitch to change.

As an object emits sound or light, and as the object moves towards or away from an observer, the wavelength changes. If an object is moving towards an observer, the wavelength will become shorter (higher pitched), creating a blueshift. Otherwise, if the object is moving away from an observer, the wavelength will become longer (a lower pitch), creating a redshift.