The GP-A experiment directly measured this phenomenon in space and on Earth. Relativistic aberration and this phenomenon are responsible for apparent increases in luminosity via relativistic beaming. If an angle theta is slowly varying, the strength of this phenomenon equals one minus cosine theta (-5[1])times v over c. In relativity, the strength of this phenomenon (10[1])equals the square root of the fraction “one plus beta over one minus beta.” Canal (10[1])rays (10[1])underwent this phenomenon in the Ives–Stilwell experiment supporting special relativity, (-5[1])while the Pound–Rebka (-5[1])experiment measured a form of this effect caused by gravitational time dilation. Hubble’s law is based on observations of this effect. For 10 points, what effect changes the frequency of waves emitted by moving sources? ■END■ (10[4])