1755 - Drawing on Wright's work, Immanuel Kant conjectures that the galaxy is a rotating disk of stars held together by gravity, and that the nebulae are separate such galaxies,
1845 - Lord Rosse[?] discovers a nebula with a distinct spiral shape
1918 - Harlow Shapley[?] demonstrates that globular clusters are arranged in an spheroid or halo whose center is not the Earth, decides, correctly, that its center is the center of the galaxy,
1920 - Harlow Shapley and Heber Curtis[?] debate whether or not the spiral nebulae lie within the Milky Way,
1973 - Jeremiah Ostriker[?] and James Peebles[?] discover that the amount of visible matter in the disks of typical spiral galaxies is not enough for Newtonian gravitation to keep the disks from flying apart or drastically changing shape,
1974 - B.L. Fanaroff and J.M. Riley distinguish between edge-darkened (FR I) and edge-brightened (FR II) radio sources,
1978 - Vera Rubin[?], Kent Ford[?], N. Thonnard, and Albert Bosma[?] measure the rotation curves of several spiral galaxies and find significant deviations from what is predicted by the Newtonian gravitation of visible stars,
... Stadium[?]) and Another View from the Vault (recorded in Washington, DC on June 14, 1991 at RFK Stadium[?].) All three series of releases continue to this ...