Herschel also studied the structure of the Milky Way and was the first to propose a model of the galaxy based on observation and measurement. He concluded that it was in the shape of a disk, but incorrectly assumed that the sun was in the centre of the disk. This heliocentric view was eventually replaced by galactocentrism due to the work of Harlow Shapley, Heber Doust Curtis and Edwin Hubble in the 1900s. All three men used significantly more far-reaching and accurate telescopes than Herschel's.