| Fifth millennium: European megalithic culture |
| Fifth-fourth millennium: passage graves |
| Fourth-third millennium: gallery graves |
| Late fourth century: henges |
| 3200 Newgrange (Ireland) and Maeshowe (Orkney) |
| 3100 Stonehenge (Wiltshire) |
| 3000 Egyptian lunar calendar |
| 2900 Egyptian solar calendar |
| 2700 Mesopotamian lunar calendar |
| 2296 Chinese recorded sighting of a comet |
| 2nd millennium: Vedas (India) |
| 1361 Chinese recorded an eclipse of the Moon |
| 1300 Shang Dynasty established the solar year at 365¼ days |
| 1217 Chinese recorded an eclipse of the Sun |
| 900 Babylonian Enuma began to take definitive form |
| 763.06.15 Assyrians recorded a solar eclipse |
| 747 Mesopotamians began to record solar and lunar eclipses |
| 624-547 Thales of Miletus said to have predicted the solar eclipse of 585 BC |
| 610-540 Anaximander of Miletus held that the origin of all things was the |
| uncreated, unlimited infinite; he believed Earth to be a cylinder at rest at |
| the centre of the infinite |
| 585-525 Anaximenes of Miletus, like Anaximander, composed a world system |
| based on an unlimited principle, which he identified as air |
| 585.05.28 Solar eclipse in Asia Minor (Thales) |
| 569-475 Pythagoras of Samos believed that all things were numbers |
| 535-475 Heraclitus of Ephesus conceived the world to be a conflict of opposites |
| regulated by a natural law (logos), which he equated with his primary cosmic |
| constituent, fire |
| 515-440 Parmenides of Elea concluded what exists must be single, indivisible and |
| unchanging and that appearances to the contrary are delusions of the senses |
| 500-428 Anaxagoras of Clazomenae believed the Sun was a hot and glowing stone |
| 5th century Babylonians used 19-year intercalation (Metonic Cycle) |
| 492-432 Empedocles of Acragas postulated four elements – earth, air, fire and |
| water |
| 490-430 Zeno of Elea defended Parmenides’ arguments |
| 480-385 Philolaus argued that all celestial objects orbit a hypothetical Central Fire |
| 432.06.27 Meton of Athens observed the summer solstice, he also mentioned the |
| nineteen-year intercalation |
| 427-347 Plato believed Earth to be stationary at the centre of the Universe |
| 408-355 Eudoxus of Cnidus developed a geometric model of the geocentric |
| universe |
| 387-312 Heraclides of Pontus is credited as being the first to suggest that the |
| apparent rotation of the sky is caused by the axial rotation of Earth |
| 384-322 Aristotle defended the doctrine that Earth is spherical: On the Heavens |
| 370-310 Callippus of Cyzicus proposed a year length of 365¼ days |
| 352 Chinese recorded a supernova (exploding star) |
| 350 Aristotle: On the Heavens |
| 325-265 Euclid: The Elements |
| 320 Chinese recorded the positions of 1464 stars in 284 constellations |
| 320-250 Aristarchus of Samos: On the Sizes and Distances of the Sun and Moon |
| He was the first to suggest the heliocentric universe |
| 275-195 Eratosthenes of Cyrene calculated circumference of Earth |
| 240-190 Apollonius of Perge studied circular motion |
| 240 Chinese recorded sighting of Halley’s Comet |
| 200 Greeks invented the astrolabe |
| 190-126 Hipparchus created the first known star catalogue |
| 165 Chinese began a continuous record of sunspots |
| 046 Julian Calendar introduced |
| 005-00-33 Jesus of Nazareth |
| 1st century: armillary spheres appeared in China |
| 1st century: Mayans used a 365-day year |
| 004-00-65 Seneca the Younger: Natural Questions |
| 008 Julian Calendar in its final form |
| 090-168 Ptolemy: Almagest, Guide to Geography, Handy Tables, Planetary Hypotheses |
| 269/70 Sphujidhvaja: Yavanajataka |
| 300-900 Mayan Calendar |
| 307-338 Yu Xi measured precession at about one degree in 50 years |
| 360-435 Macrobius described a spherical Earth at the centre of a spherical |
| universe |
| 429-501 Zu Chongzhi used precession in calendar calculations |
| 470-544 Dionysius Exiguus invented the Anno Domini (AD) era |
| 476-550 Aryabhata I: Aryabhatiya (499) |
| 480-524 Boethius translated Aristotle’s works |
| 505-587 Varahamihira: Panchasiddhantika |
| 531-579 Khosro-I commissioned translation of Greek and Syriac texts into |
| Pahlavi |
| 628 Brahmagupta: Brahmasphutasiddhanta |
| 721-725 Chinese measured one degree latitude as 155 km |
| 754-775 al-Mansur had many Syriac, Persian, Greek and Hindu documents translated into Arabic |
| 770s al-Fazari translated Sindhind (India) into Arabic |
| 858-929 al-Battani: Kitab al-Zij |
| 964 al-Sufi: Book of Fixed Stars |
| 965-1040 al-Haytham: On the Configuration of the World |
| 973-1048 al-Biruni believed that Earth rotated on its axis |
| 990-1007 ibn Yunus: Hakimi Zij |
| |
| MEDIEVAL EUROPEAN ASTRONOMY (11th-15th Century) |
| 1028-87 Arzachel: Toledan Tables |
| 1048-1131 Omar Khayyam gave improved length of the year* |
| 1054 Chinese recorded Crab Nebula on 4 July 1054 |
| 1088 Bologna University, Italy |
| 1114-87 Gerard of Cremona translated the rules for the use of the Toledan Tables |
| 1116 Kitab al-Zij (al-Battani) translated into Latin |
| 1120-25 Cairo Observatory |
| 1126 Adelard of Bath translated Sindhind (858) into Latin |
| 1150 Bhāskara II: Siddhanta Siromani |
| 1201-74 al-Tusi: Tadhkira |
| 1222 Padua University, Italy |
| 1252-84 Alfonso X (Castile & Leon) had works in Latin translated into Castilian |
| 1259 Maragha Observatory founded for al-Tusi |
| 1271 Maragha School: Ilkhanic Tables |
| 1262-72 Alfonsine Tables (sponsored by Alfonso X) |
| 1325-82 Nicolas Oresme argued that celestial phenomena would appear the same |
| if Earth made a daily rotation about its axis |
| 1343 Pisa University, Italy |
| 1340-1425 Madhava founded the Kerala School in southwest India |
| 1364 Cracow University, Poland |
| 1365 Vienna University, Austria |
| 1391 Ferrara University, Italy |
| |
| RENAISSANCE (15th-17th Century) |
| 1401-64 Nicholas of Cusa suggested that Earth moves around the Sun |
| 1409 Leipzig University, Germany |
| 1419 Rostock University, Germany |
| 1420 Samarkand Observatory built for Ulugh Beg |
| 1640s Panzano Observatory, Italy |
| 1460 Basel University, Switzerland |
| 1474 Peurbach: New Theories of the Planets |
| 1474 Regiomontanus: Calendarium and Ephemerides |
| 1477 Tubingen University, Germany |
| 1479 Copenhagen University, Denmark |
| 1496 Regiomontanus: Epitome of the Almagest |
| 1502 Wittenberg University, Austria |
| 1514 Copernicus: Commentariolus |
| 1521 Magellan observed Magellanic Clouds |
| 1540 Rheticus: First Report |
| 1543 Copernicus: The Revolutions of the Heavenly Spheres |
| 1551 Reinhold: Prutenic Tables |
| 1570s Digges probably made the first telescope |
| 1572 Tycho Brahe saw a supernova in the constellation Cassiopeia |
| 1573 Tycho Brahe: De nova stella |
| 1575-80 Istanbul Observatory |
| 1576 Frederick II built Uraniborg Observatory for Tycho |
| 1576 Fabricius discovered the variable star Mira |
| 1577 Tycho discovered comets to be celestial |
| 1578 Stjerneborg Observatory built adjacent to Uraniborg (1576) |
| 1582 Gregorian Calendar introduced |
| 1583 Tycho Brahe introduced his Tychonic System |
| 1585 Graz University, Austria |
| 1588 Tycho Brahe: De Mundi Aetherei Recentioribus Phaenomenis Liber Secundus |
| 1590 Galileo: On Motion* |
| 1596 Kepler: Mysterium Cosmographicum |
| 1600 Gilbert: The Magnet |
| |
| MODERN TIMES (17th Century – ) |
| 1602 Tycho’s star catalogue published |
| 1602 Kepler: Second Law of Planetary Motion |
| 1605 Kepler: First Law of Planetary Motion |
| 1604 Kepler’s nova |
| 1608 Lippershey applied for patent of the telescope |
| 1609 Galileo built his own telescopes |
| 1609 Kepler: Astronomia nova (first and second laws) |
| 1609 Galileo made his first observations with the telescope |
| 1610 Galileo discovered Jupiter’s moons |
| 1610 Galileo: Sidereus Nuncius |
| 1610 Galileo discovered Saturn’s rings |
| 1610 Harriot made the first known pictorial record of sunspots |
| 1611 Kepler: Dioptrice* |
| 1613 Galileo: Letters on Sunspots |
| 1614 Napier invented logarithms |
| 1619 Kepler: Harmonices mundi |
| 1619 Kepler: Third Law of Planetary Motion |
| 1627 Kepler: Rudolphine Tables |
| 1629-95 Huygens measured distance to Sirius |
| 1630 Galileo: Dialogue Concerning the Two Chief World Systems |
| 1631 Gassendi observed Venus’ transverse across the Sun |
| 1639 Horrocks observed Venus’ transverse across the Sun |
| 1644 Descartes: Principles of Philosophy |
| 1655 Huygens discovered Titan, Saturn’s largest satellite* |
| 1656 Huygens realized that Saturn is surrounded by a ring* |
| 1659 Huygens elucidated Saturn’s rings* |
| 1660 Royal Society founded |
| 1661 Cassini discovered Iapetus (Saturn moon) |
| 1662 Cassini discovered Rhea (Saturn moon) |
| 1663 James Gregory: Optica Promota |
| 1665 Royal Society published the first edition of Philosophical Transactions |
| 1665 Cassini discovered the Great Red Spot on Jupiter* |
| 1665 Newton developed a theory of colour* |
| 1667 Paris Observatory founded |
| 1667 Mira’s period identified |
| 1668 James Gregory measured the distance to Sirius |
| 1668 Newton constructed the first reflecting telescope* |
| 1668 Newton measured thedistance to Sirius as 12.6 l-y |
| 1671-3 Richer in Cayenne, French Guiana |
| 1672 Newton showed white light to be composite* |
| 1672 Newton distance to Sirius: 12.6 light-years |
| 1673 Cassini/Richer derived a distance to the Sun of 140×106 km |
| 1675 Cassini discovered the dark gap in Saturn’s rings |
| 1675 Greenwich Observatory founded |
| 1676 Ole Romer estimated the speed of light as 225,000 km/sec |
| 1677-78 Halley at St Helena |
| 1679 Halley: Catalogus Stellarum Australium |
| 1679 Jean Picard in Paris founded Connaissance des Temps (National almanac)* |
| 1680 Newton’s inverse square law explained the elliptical planetary orbits |
| discovered by Kepler |
| 1684 Cassini discovered Tethys and Dione (Saturn moons) |
| 1684 Newton: De Motu Corporum in Gyrum |
| 1687.07.05 Newton: Principia Mathematica |
| 1693 Halley discovered formula for the focal distance of a lens* |
| 1702 David Gregory: Astronomiae Elementa |
| 1704 Newton: Optics* |
| 1705 Halley: Synopsis Astronomiae Cometicae |
| 1714-1828 Board of Longitude |
| 1718 Halley discovered proper motion |
| 1721 Halley raised problem of Olbers’ paradox (1826) |
| 1725 Flamsteed: British Catalogue (posthumously) |
| 1727 Graham and Celsius showed that a disturbance on the Sun produced |
| magnetic field fluctuations on Earth |
| 1729 Bradley discovered stellar aberration |
| 1735 Harrison submitted his marine barometer (H1) to the British government’s |
| Board of Longitude |
| 1739 Dresden Codex (Maya) discovered in Vienna |
| 1750 Wright: New Hypothesis of the Universe |
| 1751-53 Lacaille at Cape of Good Hope |
| 1755 Kant: Universal History and Theory of the Heavens |
| 1757 Michell argued that most double stars are binary |
| 1759 Halley’s Comet returned |
| 1761 Trial began of Harrison’s H4 chronometer |
| 1761 Transit of Venus widely observed |
| 1764 Harrison’s son William set sail for Barbados with the fourth chronometer |
| (H4) |
| 1767 Nautical Almanac founded |
| 1767 Michell showed statistically that most star pairs are binary |
| 1767 Transit of Venus widely observed |
| 1768 Bode: Instruction for the Knowledge of the Starry Heavens (Bode’s Law) |
| 1771 Messier: Catalogue of Nebulae and Star Clusters (forty-five objects) |
| 1781 Messier’s final catalogue of nebulae |
| 1781 William Herschel discovered Uranus |
| 1783 Goodricke and Pigott suggested Algol is an eclipsing binary |
| 1783 William Herschel deduced the position of the solar apex |
| 1783-1802 William Herschel’s sweeps for nebulae |
| 1784 Cavendish using Newton’s theory of gravity calculated the gravitational |
| deflection of (corpuscular) light by the Sun |
| 1784 Goodricke discovered the periodic variation in the intensity of light from the |
| star Delta Cephei |
| 1784 Michell proposed what is now known as a black hole |
| 1785 William Herschel’s cross-section of the Galaxy |
| 1787 William Herschel discovered the two largest satellites of Uranus |
| 1789 William Herschel discovered the two satellites of Saturn |
| 1796 Laplace: Exposition du Système du Monde |
| 1799-1825 Laplace: Mécanique Céleste |
| 1800 William Herschel discovered infrared radiation |
| 1801 Piazzi discovered the first asteroid Ceres |
| 1801 Ritter discovered ultraviolet light |
| 1801 Johann Soldner using Newton’s theory calculated the gravitational deflection |
| of (particle) light by the Sun* |
| 1801 Young established the wave theory of light |
| 1802 Olbers discovered the second asteroid Pallas |
| 1802 William Herschel discovered binary stars, catalogued 848 stars |
| 1802 Wollaston observed the dark lines on the spectrum |
| 1804 Harding discovered the third asteroid Juno |
| of 5.2 seconds of arc/year |
| 1809 Gauss The Theory of the Motion of Celestial Bodies (least squares method) |
| 1814 Fraunhofer catalogued more than 300 absorption lines in the spectrum of |
| visible light |
| 1818 Bessel: Fundamenta astronomiae |
| 1820 Royal Astronomical Society founded |
| 1826 Lobachevsky discovered hyperbolic non-Euclidean geometry |
| 1826 Olbers discussed the paradox that now bears his name |
| 1832 Janos Bolyai independently described non-Euclidian geometry* |
| 1834-38 John Herschel at Cape of Good Hope |
| 1837 Struve announced parallax of Vega |
| 1838 Bessel measured the annual parallax of the star 61 Cygni as 0.31 seconds of |
| arc, very close to the modern value of 0.287, corresponding to a distance of 11.4 |
| light-years |
| 1839 Henderson measured the parallax of Alpha Centauri, which is just 4.29 light- |
| years away |
| 1840 Struve reported his measurement of the bright star Vega |
| 1842 Doppler described the phenomenon that now bears his name |
| 1842 Observers noted corona and prominences during solar eclipse |
| 1843 Schwabe: Solar Observations. He suggested that the sunspots wax and wan on a ten-year cycle |
| 1845 Parsons used his reflecting telescope to resolve the nebula M31 into a spiral |
| shape that he attributed to its rotation |
| 1845 Joseph predicted the position of a large planet beyond Uranus, whose |
| gravitational tugs on Uranus |
| 1846 Galle found Neptune (presence as mathematically predicted) |
| 1847 Galloway: On the Proper Motion of the Solar System |
| 1848 Fizeau described redshift and blueshift |
| 1852 Sabine announced sunspots linked with magnetic storms |
| 1856 Pogson proposed star magnitude scale |
| 1857 Maxwell showed that Saturn’s rings made of particles |
| 1859 Bunsen and Kirchhoff in the laboratory associated elements with spectral |
| lines |
| 1859 Carrington and Hodgson observed a disturbance on the Sun was followed |
| seventeen hours later by a magnetic storm on Earth |
| 1860s Huggins showed the stars to be composed of known elements occurring on Earth and in the Sun |
| 1861/2 Maxwell published early form of ‘Maxwell equations’ |
| 1863 Angstrom showed hydrogen present in solar atmosphere |
| 1864 Huggins showed a nebula to be formed of gas |
| 1868 Angstrom: Recherches sur le Spectre Solaire |
| 1868 Huggins was able to infer that Sirius was moving away from the Sun at twenty-five miles per second |
| 1868 Janssen discovered Helium (Lockyer) on the Sun (1895) |
| 1868 Secchi created a spectral classification of stars |
| 1868 Secchi described four types of stellar spectra* |
| 1872 Draper made the first photograph of a stellar spectrum (Vega). |
| 1873 Maxwell: A Treatise on Electricity and Magnetism |
| 1877 Hall discovered two moons on Mars* |
| 1883 Mach: The Science of Mechanics |
| 1884 Greenwich Mean Time fixed as the prime meridian |
| 1887 Michelson-Morley experiment disproved the existence of an ether, the |
| medium through which light was supposed to travel |
| 1887 Pickering initiated study of spectroscopic binaries |
| 1888 Vogel detected Doppler shifts in stellar spectra which enabled him to |
| measure radial velocities |
| 1888 Dreyer published his New General Catalogue (NGC) of the apparent brightness |
| and celestial positions of thousands of nebulae and star clusters |
| 1889 Barnard took the first photographs of Milky Way |
| 1889 Fitzgerald proposed that a body’s length shortens in its direction of motion |
| (noticeable only near the speed of light) |
| 1890 Michelson described the use of interference methods to measure the angular |
| size and the brightness of cosmic sources too small to be resolved by a single |
| telescope |
| 1890 Lockyer: Meteoritic Hypothesis* |
| 1891 Wolf instituted programme of photography to find asteroids |
| 1894 Riemann devised a system of non-Euclidean geometry |
| 1895 Ramsay discovered Helium on Earth |
| 1895 Lorenz independently develops the concept that a body’s length shortens in |
| its direction of motion |
| 1898 Keeler began a systematic photography of nebulae using the refracting |
| telescope at Lick Observatory |
| 1900 Planck proposed his black-body radiation law |
| 1905 Einstein proposed his Special Theory of Relativity |
| 1906 Kapteyn began to map the size and shape of the Galaxy |
| 1907 Einstein derived his celebrated equation E=mc2 |
| 1908 Minkowski introduced the concept of spacetime |
| 1911 Hertzsprung published a diagram of the absolute luminosity of stars plotted |
| against their spectral type or effective temperature |
| 1912 Leavitt discovered a period-luminosity relation for Cepheid variable stars in |
| the Small Magellanic Cloud km/s |
| 1913 Russell independently produced a similar diagram to that of Hertzsprung |
| 1914 Slipher announced large radial velocities of spiral nebulae |
| 1915 Einstein published a paper on the General Theory of Relativity |
| 1916 Barnard discovered the star that bears his name |
| 1916 Schwarzschild calculated that there is a critical radius for the event of a black |
| hole |
| 1917 Sitter proposed a possible cosmological model that was later used by |
| Eddington* and predicted an expanding Universe |
| 1918 First version of the Henry Draper Catalogue published, giving spectroscopic |
| classifications for 225,300 stars |
| 1918 Shapley discovered the large size and distant centre of the Galaxy |
| 1919 Lundmark measured the distance to the Andromeda Galaxy to be 650,000 |
| light years |
| 1920 ‘Great Debate‘ between Shapley and Curtis |
| 1920 Meghnad Saha published theory of ionization in stellar atmospheres* |
| 1922 Friedmann published his solutions to Einstein’s equations |
| 1922 Opik estimated the distance of the Andromeda to be 1,400,000 light years |
| 1924 Hubble found a Cepheid variable in Andromeda nebula |
| 1925 Hubble demonstrated Andromeda nebula is an independent galaxy |
| 1927 Heisenberg published his uncertainty principle |
| 1927 Lemaitre proposed what became known as the Big Bang Theory |
| 1927 Oort analysed stellar motions to study structure of the Galaxy |
| 1929 Hubble established relationship between redshift and distance of galaxies |
| (Hubble’s law) |
| 1930 Tombaugh found Pluto (presence predicted mathematically) |
| 1930 Trumpler demonstrated existence of interstellar gas in plane of the |
| Galaxy |
| 1931 Jansky founded radio astronomy |
| 1932 Jansky detected radio waves from Milky Way |
| 1933 Zwicky inferred the existence of dark matter |
| 1937 Reber built the first dedicated radio telescope |
| 1937 Reinmuth discovered the asteroid Hermes |
| 1943 Baade identified two different star populations in Andromeda |
| 1944 Hulst predicted hydrogen should emit 21-cm radiation |
| 1946 Dicke predicted a cosmic microwave background radiation temperature of 20 |
| Kelvin |
| 1948 Alpher/Bethe/Gamow published their work ‘The Origin of Chemical Element‘ in |
| the Physical Review (April)* |
| 1948 Hoyle/Bondi/Gold proposed the Steady State theory |
| 1950s Vaucouleurs promoted the idea of superclusters |
| 1951 Ewen and Purcell detected 21-cm emission from interstellar hydrogen |
| clouds |
| 1951 Hulst and Oort used Doppler shifts in hydrogen emission to examine the |
| Galaxy’s structure |
| 1951 Salpeter suggested the triple-alpha process |
| 1952 Baade calculated the distance to Andromeda Galaxy to be two million light |
| years |
| 1957 Lovell telescope at Jodrell Bank completed |
| 1958 Sandage estimated age of Universe to be at least thirteen billion (13×109) |
| years |
| 1960s Penzias/Wilson detect a cosmic radio noise of about 3 Kelvin |
| 1963 First quasar discovered |
| 1965 Penrose proved that singularities (such as black holes) could be formed from |
| the gravitational collapse of immense dying stars |
| 1967 First pulsar discovered |
| 1979 Guth proposed the inflationary phase of Big Bang |
| 1983 Linde proposed chaotic inflation |
| 1986 Halley’s Comet returned |
| 1988 Hawking: A Brief History of Time* |
| 1990 Hubble Space telescope launched |
| 1992 Smoot found ripples from Big Bang |
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