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

Part of a series on
Physical cosmology
Big Bang · Universe Age of the universe Chronology of the universe
Early universe Inflation · Nucleosynthesis Backgrounds Gravitational wave (GWB) Microwave (CMB) · Neutrino (CNB)
Expansion · Future Hubble's law · Redshift Expansion of the universe FLRW metric · Friedmann equations Inhomogeneous cosmology Future of an expanding universe Ultimate fate of the universe
Components · Structure Components Lambda-CDM model Dark energy · Dark matter Structure Shape of the universe Galaxy filament · Galaxy formation Large quasar group Large-scale structure Reionization · Structure formation
Experiments Black Hole Initiative (BHI) BOOMERanG Cosmic Background Explorer (COBE) Dark Energy Survey Planck space observatory Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey ("2dF") Wilkinson Microwave Anisotropy Probe (WMAP)
Scientists Aaronson Alfvén Alpher Copernicus de Sitter Dicke Ehlers Einstein Ellis Friedmann Galileo Gamow Guth Hawking Hubble Huygens Kepler Lemaître Mather Newton Penrose Penzias Rubin Schmidt Smoot Suntzeff Sunyaev Tolman Wilson Zeldovich List of cosmologists
Subject history Discovery of cosmic microwave background radiation History of the Big Bang theory Timeline of cosmological theories
Category Astronomy portal
v t e

The following is a timeline of galaxies, clusters of galaxies, and large-scale structure of the universe.

Pre-20th century

• 5th century BC — Democritus proposes that the bright band in the night sky known as the Milky Way might consist of stars.
• 4th century BC — Aristotle believes the Milky Way to be caused by "the ignition of the fiery exhalation of some stars which were large, numerous and close together" and that the "ignition takes place in the upper part of the atmosphere, in the region of the world which is continuous with the heavenly motions".^[1]
• 964 —
  Book of Fixed Stars
  , and which are the first galaxies other than the Milky Way to recorded.
• 11th century — Al-Biruni, another Persian astronomer, describes the Milky Way galaxy as a collection of fragments of numerous nebulous stars.^[5]
• 11th century —
  Arabian astronomer, refutes Aristotle's theory on the Milky Way by making the first attempt at observing and measuring the Milky Way's parallax,^[6] and he thus "determined that because the Milky Way had no parallax, it was very remote from the Earth and did not belong to the atmosphere".^[7]
• 12th century —
  Earth's atmosphere.^[1]
• 14th century — Ibn Qayyim al-Jawziyya of Syria proposes the Milky Way galaxy to be "a myriad of tiny stars packed together in the sphere of the fixed stars" and that these stars are larger than planets.^[8]
• 1521 — Ferdinand Magellan observes the Magellanic Clouds during his circumnavigating expedition.^[9]
• 1610 — Galileo Galilei uses a telescope to determine that the bright band on the sky, the "Milky Way", is composed of many faint stars.
• 1612 — Simon Marius using a moderate telescope observes Andromeda and describes as a "flame seen through horn".^[10]
• 1750 — Thomas Wright discusses galaxies and the flattened shape of the Milky Way and speculates nebulae as separate.^[11]
• 1755 —
  Island Universes
  .
• 1774 — Charles Messier releases a preliminary list of 45 Messier objects, three of which turn out to be the galaxies including Andromeda and Triangulum. By 1781 the final published list grows to 103 objects, 34 of which turn out to be galaxies.
• 1785 — William Herschel carried the first attempt to describe the shape of the Milky Way and the position of the Sun in it by carefully counting the number of stars in different regions of the sky. He produced a diagram of the shape of the galaxy with the solar system close to the center.
• 1845 — Lord Rosse discovers a nebula with a distinct spiral shape.

Early 20th century

• 1912 —
  Doppler shifts
  indicating recessional velocity.
• 1917 —
  Heber Curtis finds novae in Andromeda Nebula M31 were ten magnitudes fainter than normal, giving a distance estimate of 150,000 parsecs
  supporting the "island universes" or independent galaxies hypothesis for spiral nebulae.
• 1918 — Harlow Shapley demonstrates that globular clusters are arranged in a spheroid or halo whose center is not the Earth, and hypothesizes, correctly, that its center is the Galactic Center of the galaxy,
• 26 April 1920 — Harlow Shapley and
  Heber Curtis debate
  whether Andromeda Nebula is within the Milky Way. Curtis notes dark lanes in Andromeda resembling the dust clouds in the Milky Way, as well as significant Doppler shift.
• 1922 — Ernst Öpik distance determination supports Andromeda as extra-galactic object.
• 1923 — Edwin Hubble resolves the Shapley–Curtis debate by finding Cepheids in the Andromeda Galaxy, definitively proving that there are other galaxies beyond the Milky Way.
• 1930 —
  interstellar dust in the galactic plane
  ; this absorption had plagued earlier models of the Milky Way.
• 1932 — Karl Guthe Jansky discovers radio noise from the center of the Milky Way.
• 1933 — Fritz Zwicky applies the virial theorem to the Coma Cluster and obtains evidence for unseen mass.
• 1936 — Edwin Hubble introduces the spiral, barred spiral, elliptical, and irregular galaxy classifications.
• 1939 — Grote Reber discovers the radio source Cygnus A.
• 1943 —
  emission lines, named Seyfert galaxies
  ,
• 1949 — J. G. Bolton, G. J. Stanley, and O. B. Slee identify
  NGC 5128
  as extragalactic radio sources.

• 1953 — Gérard de Vaucouleurs discovers that the galaxies within approximately 200 million light-years of the Virgo Cluster are confined to a giant supercluster disk.
• 1954 — Walter Baade and Rudolph Minkowski identify the extragalactic optical counterpart of the radio source Cygnus A.
• 1959 — Hundreds of radio sources are detected by the Cambridge Interferometer which produces the 3C catalogue. Many of these are later found to be distant quasars and radio galaxies.
• 1960 —
  Thomas Matthews determines the radio position of the 3C source 3C 48
  to within 5".
• 1960 — Allan Sandage optically studies 3C 48 and observes an unusual blue quasistellar object.
• 1962 —
  lunar occultations to determine a precise position for the quasar 3C 273
  and deduce that it is a double source.
• 1962 —
  galaxy formation
  by a single (relatively) rapid monolithic collapse, with the halo forming first, followed by the disk.
• 1963 — Maarten Schmidt identifies the redshifted Balmer lines from the quasar 3C 273.
• 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.
• 1973 — Donald Gudehus finds that the diameters of the brightest cluster galaxies have increased due to merging, the diameters of the faintest cluster galaxies have decreased due to tidal distention, and that the Virgo cluster has a substantial peculiar velocity.
• 1974 —
  distinguish
  between edge-darkened (FR I) and edge-brightened (FR II) radio sources.
• 1976 —
  Robert Jackson discover the Faber-Jackson relation between the luminosity of an elliptical galaxy and the velocity
  dispersion in its center. In 1991 the relation is revised by Donald Gudehus.
• 1977 —
  rotation curve
  .
• 1978 — Steve Gregory and Laird Thompson describe the Coma supercluster.
• 1978 — Donald Gudehus finds evidence that clusters of galaxies are moving at several hundred kilometers per second relative to the cosmic microwave background radiation.
• 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.
• 1978 —
  galaxy formation
  occurs through the merger of smaller groups.

Late 20th century

This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (April 2009) (Learn how and when to remove this message)

• 1981 — Robert Kirshner, August Oemler, Paul Schechter, and Stephen Shectman find evidence for a giant void in Boötes, 250 to 330 million light years across.^[12]
• 1985 —
  polarized
  reflected light.
• 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.
• 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 Hydra and Centaurus.
• 1987 — R. Brent Tully discovers the Pisces–Cetus Supercluster Complex, a structure one billion light years long and 150 million light years wide.
• 1989 —
  Great Wall
  ", a sheet of galaxies more than 500 million light years long and 200 million wide, but only 15 million light years thick.
• 1990 — Michael Rowan-Robinson and Tom Broadhurst discover that the IRAS galaxy IRAS F10214+4724 is the brightest known object in the Universe.
• 1991 — Donald Gudehus discovers a serious systematic bias in certain cluster galaxy data (surface brightness vs. radius parameter, and the ${\displaystyle D_{n}}$ method) which affect galaxy distances and evolutionary history; he devises a new distance indicator, the reduced galaxian radius parameter, ${\displaystyle r_{g}}$, which is free of biases.
• 1992 — First detection of large-scale structure in the cosmic microwave background indicating the seeds of the first clusters of galaxies in the early Universe.
• 1995 — First detection of small-scale structure in the cosmic microwave background.
• 1995 — Hubble Deep Field survey of galaxies in field 144 arc seconds across.
• 1998 — The 2dF Galaxy Redshift Survey maps the large-scale structure in a section of the Universe close to the Milky Way.
• 1998 — The Hubble Deep Field South is compiled.
• 1998 — Discovery of
  accelerating universe.^[13]
• 2000 — Data from several cosmic microwave background experiments give strong evidence that the Universe is "flat" (space is not curved, although space-time is), with important implications for the formation of large-scale structure

Early 21st century

• 2001 — First data release from the ongoing Sloan Digital Sky Survey
• 2004 — The European Southern Observatory discovers Abell 1835 IR1916, the most distant galaxy yet seen from Earth.
• 2004 — The Arcminute Microkelvin Imager begins to map the distribution of distant clusters of galaxies
• 2005 —
  Milky Way Galaxy is a barred spiral galaxy.^[14][15][16]
• 2012 — Astronomers report the discovery of the most distant dwarf galaxy yet found, approximately 10 billion light-years away.^[17]
• 2012 — The Huge-LQG, a large quasar group, one of the largest known structures in the universe, is discovered.^[18]
• 2013 — The galaxy
  comoving distance).^[19]
• 2013 — The Hercules–Corona Borealis Great Wall, a massive galaxy filament and the largest known structure in the universe, was discovered through gamma-ray burst mapping.^[20][21][22]
• 2014 — The Laniakea Supercluster, the galaxy supercluster that is home to the Milky Way is defined via a new way of defining superclusters according to the relative velocities of galaxies.^[23][24] The new definition of the local supercluster subsumes the prior defined local supercluster, the Virgo Supercluster, as an appendage.^{[25][26][27][28][29]}
• 2020 — Astronomers report the discovery of a large cavity in the
  jets, possibly as a result of a spike in supply of gas to the black hole that could have occurred if a galaxy fell into the centre of the cavity.^[30][31][32]
• 2020 — Astronomers report to have discovered the
  Wolfe Disk, dating back to when the universe was only 1.5 billion years old, possibly indicating the need to revise theories of galaxy formation and evolution.^{[33][34][35][36]}
• 2020 — The South Pole Wall is a massive cosmic structure formed by a giant wall of galaxies (a galaxy filament) that extends across at least 1.37 billion light-years of space, and is located approximately a half billion light-years away.^{[37][38][39][40][41][42]}
• 2020 — After a 20-year-long survey, astrophysicists of the Sloan Digital Sky Survey publish the largest, most detailed 3D map of the universe so far, fill a gap of 11 billion years in its expansion history, and provide data which supports the theory of a flat geometry of the universe and confirms that different regions seem to be expanding at different speeds.^[43][44]
• 2022 — James Webb Space Telescope (JWST) releases the Webb's First Deep Field.
• 2022 — JWST detects CEERS-93316, a candidate high-redshift galaxy, with an estimated redshift of approximately z = 16.7, corresponding to 235.8 million years^[45] after the Big Bang.^[46] If confirmed, it is one of the earliest and most distant known galaxies observed.^[47]

See also

• Illustris project
• Large-scale structure of the cosmos
• Timeline of astronomical maps, catalogs, and surveys
• Timeline of cosmological theories
• UniverseMachine
• List of largest cosmic structures

References