I've done a little diagram to hopefully represent my question. I've represented three different sources on three moving vehicles: Source 1: cannon (emitting cannon ball) Source 2: horn (emitting sound) Source 3: light (emitting light) For the cannon the cannon ball will reach the target sooner than a cannon ball fired from a stationary cannon. For the horn the sound will reach the target at the same time as sound from a stationary horn. For the torch the light will reach the target (at the same time)/(sooner than) light from a stationary torch? Could someone with enough credentials just clear up for me once and for all what the answer is for the last one? Will the light from the moving torch reach the target at the same time as the light from a stationary torch or would it reach the target sooner than the light from the stationary torch?