A distant galaxy emits light that has a wavelength of 557.1 nm. On earth, the wavelength of this light is measured to be 560.8 nm.
(a) Decide whether this galaxy is approaching or receding from the earth.
(b) Find the speed of the galaxy relative to the earth. (Give your answer to 4 significant digits. Use 2.998 × 108 m/s as the speed of light.)