Shown an animation of a planet and star orbiting their center of mass, the student is asked to determine the wavelength shift (Doppler effect; red shift, blue shift, unshifted) in the star's spectrum for different positions in its and in the planet's orbit, relative to Earth.
keywords: Doppler effect, center of mass, red shift, blue shift
swf file: ca_extrasolarplanets_espdopplershift.swf