Redshift is an increase in wavelengths and a decrease in frequency. As an object moves further away from a reference point, all waves emitted from that object h

Redshift is an increase in wavelengths and a decrease in frequency. As an object moves further away from a reference point, all waves emitted from that object have an increased wavelength. Imagine a basketball player bouncing a ball up and down at a fix frequency. The wavelength is inversely proportional to the frequency. The wave here is the ball bouncing up and down. Now imagine the moment the ball hits the ground they start moving away from you at a fixed speed. Because they have accelerated, light now needs to travel some additional distance since the ball at the top is further away from you than the ball at the bottom was. But their new frequency remains the same because the displacement is now accounted for in the wavelength. If they stop moving, opposite happens and it blueshifts. If they keep accelerating, the distance increases and so does the redshifting.