The observed wavelength of light is longer when objects are moving away from us. The light is shifted towards the red end of the visible spectrum. This phenomenon is known as Red Shift. This is one of the evidences that is used to support the Big Bang Theory. It seems that the light traveling from distant galaxies is red shifted, which means the universe is expanding from an initial point, to what we observe today and all the objects are moving away. The fact that the further the galaxy from us is, the greater the red shift, means that the more distant the galaxy, the faster it is moving.