SPECTRAL DATA
Spectral Data helps us determine how fast a galaxy is moving, how far away it is, and where it is moving. Since we know what stars are made of, we can use the spectral signatures of the same gasses in a lab to determine the shift of the signature, or the Red Shift of the object. Hydrogen is the big one. Hydrogen has a very distinct spectral signature of 650, since we know that stars are comprised primarily of hydrogen, we can use the spectral signature of a far away galaxy, compare it to hydrogen, and determine the Red Shift. Edwin Hubble found that the vast majority of galaxies he viewed were Red Shifted, and therefore moving away (See RED SHIFT) in fact, there are only about 100 galaxies we know of today that are Blue Shifted. Just because everything is moving away from Earth, doesn't mean that Earth is the center of the Universe. Everything is moving away from everything else no matter where you put the center point. The universe is infinitely expanding away from itself.