Simplify the following text for a Grade 14 native English-speaking person.
Original: He also discovered that the degree of `` Doppler shift '' ( `` redshift '' ) the change in pitch or color when an object or incoming sound moves closer ( higher pitch , brighter color ) or further away ( lower and darker ) observed in the light spectra from other galaxies increased in proportion to a particular galaxy 's distance from Earth .
Simplified: He also discovered that the degree of `` Doppler shift '' ( specifically `` redshift '' ) observed in the light spectra from other galaxies increased in proportion to a particular galaxy 's distance from Earth .