Timeline of Galaxies, Clusters of Galaxies, and Large-scale Structure

Timeline of knowledge about galaxies, clusters of galaxies, and large-scale structure

1. 1521 – Ferdinand Magellan observes the Magellanic Clouds during his
   circumnavigating expedition,
2. 1610 – Galileo Galilei uses a telescope to determine that the bright
   band on the sky, the “Milky Way”, is composed of many faint stars,
3. 1750 – Thomas Wright discusses galaxies and the shape of the Milky Way,
4. 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,
5. 1845 – Lord Rosse discovers a nebula with a distinct spiral shape
6. 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,
7. 1920 – Harlow Shapley and Heber Curtis debate whether or not the spiral
   nebulae lie within the Milky Way,
8. 1923 – Edwin Hubble resolves the Shapely-Curtis debate by finding
   Cepheids in Andromeda,
9. 1930 – Robert Trumpler uses open cluster observations to quantify the
   absorption of light by interstellar dust in the galactic plane; this
   absorption had plagued earlier models of the Milky Way,
10. 1932 – Karl Guthe Jansky discovers radio noise from the center of the
    Milky Way,
11. 1933 – Fritz Zwicky applies the virial theorem to the Coma cluster and
    obtains evidence for unseen mass,
12. 1936 – Edwin Hubble introduces the spiral, barred spiral, elliptical,
    and irregular galaxy classifications,
13. 1939 – Grote Reber discovers the radio source Cygnus A,
14. 1943 – Carl Keenan Seyfert identifies six spiral galaxies with
    unusually broad emission lines, named Seyfert galaxies,
15. 1949 – J.G. Bolton, G.J. Stanley, and O.B. Slee identify NGC 4486 (M87)
    and NGC 5128 as extragalactic radio sources,
16. 1953 – Gerard de Vaucouleurs discovers that the galaxies within
    approximately 200 million light years of the Virgo cluster are confined
    to a giant supercluster disk,
17. 1954 – Walter Baade and Rudolph Minkowski identify the extragalactic
    optical counterpart of the radio source Cygnus A,
18. 1960 – Thomas Matthews determines the radio position of 3C48 to within
    5″,
19. 1960 – Allan Sandage optically studies 3C48 and observes an unusual
    blue quasistellar object,
20. 1962 – Cyril Hazard, M.B. Mackey, and A.J. Shimmins use lunar
    occultations to determine a precise position for the quasar 3C273 and
    deduce that it is a double source,
21. 1963 – Maarten Schmidt identifies the redshifted Balmer lines from the
    quasar 3C273
22. 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,
23. 1974 – B.L. Fanaroff and J.M. Riley distinguish between edge-darkened
    (FR I) and edge-brightened (FR II) radio sources,
24. 1976 – Sandra Faber and Robert Jackson discover the Faber-Jackson
    relation between the luminosity of an elliptical galaxy and the
    velocity dispersion in its center,
25. 1977 – Brent Tully and Richard Fisher discover the Tully-Fisher
    relation between the luminosity of an isolated spiral galaxy and the
    velocity of the flat part of its rotation curve,
26. 1978 – Steve Gregory and Laird Thompson describe the Coma supercluster,
27. 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,
28. 1981 – Robert Kirshner, August Oemler, Paul Schechter, and Stephen
    Shectman find evidence for a giant void in Bootes with a diameter of
    approximately 100 million light years,
29. 1985 – Robert Antonucci and J. Miller discover that the Seyfert II
    galaxy NGC 1068 has broad lines which can only be seen in polarized
    reflected light,
30. 1986 – Amos Yahil, David Walker, and Michael Rowan-Robinson find that
    the direction of the IRAS galaxy density dipole agrees with the
    direction of the cosmic microwave background temperature dipole,
31. 1987 – David Burstein, Roger Davies, Alan Dressler, Sandra Faber,
    Donald Lynden-Bell, R.J. Terlevich, and Gary Wegner claim that a large
    group of galaxies within about 200 million light years of the Milky Way
    are moving together towards the “Great Attractor in the direction of
    the Hydra and Centaurus,
32. 1989 – Margaret Geller and John Huchra discover the “Great Wall”, a
    sheet of galaxies more than 500 million light years long and 200
    million wide, but only 15 million light years thick,
33. 1990 – Michael Rowan-Robinson and Tom Broadhurst discover that the IRAS
    galaxy F10214+4724 is the brightest known object in the Universe.