RED SHIFT
Red shift refers to the displacement of spectral signature towards longer wavelengths. The lower the frequency, the longer the wavelength. Longer wavelengths appear Red to the human eye, and shorter wavelengths appear bluer, or more purple. Red shift is used to determine the velocity of distant galaxies and other celestial bodies based on the signature of their radiation. The faster something is moving away from us, the more the signature will be shifted to the Red side of the spectrum. Red shift focuses on the distinctive spectral signature of Hydrogen. The same rules apply to when an object is moving toward you, the waves shorten and are displaced to the blue end of the spectrum. This is called "Blue Shift". The frequency of stars also applies to Red Shift. The bigger and hotter the star, the bluer it will appear, the smaller and cooler the star, the redder it will appear. Very hot stars emit blue, high frequency light, and cool stars emit red, low frequency light.