He is attributed with defining that galaxies revolve, and was capable to determine the velocities at which they rotate. Slipher had discover that most galaxies presented a redshift in their spectrum, representing that they were all moving away from us in interstellar, or retreating (Slipher, 1915). By computing the magnitude of the redshift, he was capable to control the recessional velocity or the speediness at which matters were "flying." Slipher had made a clarification from his observations that put a new standpoint on the universe, and in reply, he established a standing ovation for his demonstration.