6th century BCE — The Babylonian world map shows the Earth surrounded by the cosmic ocean, with seven islands arranged around it so as to form a seven-pointed star. Contemporary Biblical cosmology reflects the same view of a flat, circular Earth swimming on water and overarched by the solid vault of the firmament to which are fastened the stars.
4th century BCE — De Mundo - Five elements, situated in spheres in five regions, the less being in each case surrounded by the greater — namely, earth surrounded by water, water by air, air by fire, and fire by ether — make up the whole Universe.
6th century — John Philoponus proposes a universe that is finite in time and argues against the ancient Greek notion of an infinite universe
Revealed in the 6th century, the Qur'an mentions Chapter 21: Verse 30 - "Have those who disbelieved not considered that the heavens and the earth were a joined entity, and We separated them ... "
ca. 8th century — Puranic Hindu cosmology, in which the Universe goes through repeated cycles of creation, destruction and rebirth, with each cycle lasting 4.32 billion years.
9th-12th centuries — Al-Kindi (Alkindus), Saadia Gaon (Saadia ben Joseph) and Al-Ghazali (Algazel) support a universe that has a finite past and develop two logical arguments against the notion of an infinite past, one of which is later adopted by Immanuel Kant
12th century — Fakhr al-Din al-Razi discusses Islamic cosmology, rejects Aristotle's idea of an Earth-centered universe, and, in the context of his commentary on the Qur'anic verse, "All praise belongs to God, Lord of the Worlds," proposes that the universe has more than "a thousand thousand worlds beyond this world such that each one of those worlds be bigger and more massive than this world as well as having the like of what this world has." He argued that there exists an infinite outer space beyond the known world, and that there could be an infinite number of universes.
1584 — Giordano Bruno proposes a non-hierarchical cosmology, wherein the Copernican solar system is not the center of the universe, but rather, a relatively insignificant star system, amongst an infinite multitude of others
1610 — Johannes Kepler uses the dark night sky to argue for a finite universe
1687 — Sir Isaac Newton's laws describe large-scale motion throughout the universe
1837 - Following over 100 years of unsuccessful attempts, Friedrich Bessel, Thomas Henderson and Otto Struve measure the parallax of a few nearby stars; this is the first measurement of any distances outside the solar system.
1923 — Edwin Hubble measures distances to a few nearby spiral nebulae (galaxies), the Andromeda Galaxy (M31), Triangulum Galaxy (M33), and NGC 6822. The distances place them far outside our Milky Way, and implies that fainter galaxies are much more distant, and the universe is composed of many thousands of galaxies.
1927 — Georges Lemaître discusses the creation event of an expanding universe governed by the Einstein field equations. From its solutions to the Einstein equations, he predicts the distance-redshift relation.
1928 — Howard P. Robertson briefly mentions that Vesto Slipher's redshift measurements combined with brightness measurements of the same galaxies indicate a redshift-distance relation
1929 — Edwin Hubble demonstrates the linear redshift-distance relation and thus shows the expansion of the universe
1980 — Alan Guth and Alexei Starobinsky independently propose the inflationary Big Bang universe as a possible solution to the horizon and flatness problems.
1981 — Viacheslav Mukhanov and G. Chibisov propose that quantum fluctuations could lead to large scale structure in an inflationary universe.
1982 — The first CfA galaxy redshift survey is completed.
1982 — Several groups including James Peebles, J. Richard Bond and George Blumenthal propose that the universe is dominated by cold dark matter.
1983 - 1987 — The first large computer simulations of cosmic structure formation are run by Davis, Efstathiou, Frenk and White. The results show that cold dark matter produces a reasonable match to observations, but hot dark matter does not.
1988 — Measurements of galaxy large-scale flows provide evidence for the Great Attractor.
1990 — Preliminary results from NASA's COBE mission confirm the cosmic microwave background radiation has a blackbody spectrum to an astonishing one part in 105 precision, thus eliminating the possibility of an integrated starlight model proposed for the background by steady state enthusiasts.
1992 — Further COBE measurements discover the very small anisotropy of the cosmic microwave background, providing a "baby picture" of the seeds of large-scale structure when the universe was around 1/1100th of its present size and 380,000 years old.
1996 — The first Hubble Deep Field is released, providing a clear view of very distant galaxies when the universe was around one-third of its present age.
1998 — Controversial evidence for the fine structure constant varying over the lifetime of the universe is first published.
1999 — Measurements of the cosmic microwave background radiation with finer resolution than COBE, (most notably by the BOOMERanG experiment see Mauskopf et al., 1999, Melchiorri et al., 1999, de Bernardis et al. 2000) provide evidence for oscillations (the first acoustic peak) in the anisotropy angular spectrum, as expected in the standard model of cosmological structure formation. The angular position of this peak indicates that the geometry of the universe is close to flat.
2002 — The Cosmic Background Imager (CBI) in Chile obtained images of the cosmic microwave background radiation with the highest angular resolution of 4 arc minutes. It also obtained the anisotropy spectrum at high-resolution not covered before up to l ~ 3000. It found a slight excess in power at high-resolution (l > 2500) not yet completely explained, the so-called "CBI-excess".
2003 — NASA's Wilkinson Microwave Anisotropy Probe (WMAP) obtained full-sky detailed pictures of the cosmic microwave background radiation. The images can be interpreted to indicate that the universe is 13.7 billion years old (within one percent error), and are very consistent with the Lambda-CDM model and the density fluctuations predicted by inflation.
2006 — The long-awaited three-year WMAP results are released, confirming previous analysis, correcting several points, and including polarization data.
2006–2011 — Improved measurements from WMAP, new supernova surveys ESSENCE and SNLS, and baryon acoustic oscillations from SDSS and WiggleZ, continue to be consistent with the standard Lambda-CDM model.
Bunch, Bryan, and Alexander Hellemans, "The History of Science and Technology: A Browser's Guide to the Great Discoveries, Inventions, and the People Who Made Them from the Dawn of Time to Today". ISBN0-618-22123-9
P. Mauskopf et al.,astro-ph/9911444, Astrophys. J. 536 (2000) L59-L62.
A. Melchiorri et al.,astro-ph/9911445, Astrophys. J. 536 (2000) L63-L66.
P. de Bernardis et al., astro-ph/0004404, Nature 404 (2000) 955-959.
A. Readhead et al., Polarization observations with the Cosmic Background Imager, Science 306 (2004), 836-844.