It is believed that the great mass of the stars … are arranged in the form of a lens- or bun-shaped system. … considerably flattened towards one plane … the Sun occupies a fairly central position. … towards the galactic poles the density continues practically uniform up to a distance of about 100 parsecs; after that the falling off becomes noticeable, so that at 300 parsecs it is only a fraction (perhaps a fifth) of the density near the Sun. [One parsec equals 3.26 light years.] The extension in the galactic plane is at least three times greater. These figures are subject to large uncertainties.
       —Eddington