Astronomical Timeline

c. 15000 BC: Drawings in the cave of Lascaux may be of constellations. However, this is fairly unlikely as there are no other findings to make this plausible.
c. 7000 BC: Drawing in Chanchal de Mahoma (Spain) representing the phases of the Moon.
4800 BC: Calendar stone near the border between Egypt and Sudan.
4500 BC: Stone structures with an astronomical connection in Carnac, France.
4004 BC: On 23 October at 0900, the Universe was created, according to the Anglican Archbishop of Armagh, James Ussher.
c. 3000 BC: The Sumerians make lists of bright stars and give the first names to constellations in the zodiac. They also record the movements of the five visible planets.
c. 2600 BC: Religion based on observations of stars reaches its zenith in Egypt during the 3^rd dynasty. Later replaced by sun worship.
2485 - 2375 BC: The large pyramids in Egypt, which were directed towards the points of the compass by means of stellar observations.
c. 2354 BC: The first known female astronomer, En Hedu'anna, lived in Babylon and was the daughter of Sargon.
c. 2300 BC: Chinese sources report observations. The first recorded observation of a comet is from 2296 BC. A solar eclipse is recorded in 2137 BC.
c. 2000 BC: The oldest written sources from Babylon, including observation of a lunar eclipse.
c. 1900 BC: Stonehenge. The construction period lasted from c. 3100 BC to c. 1500 BC.
c. 1600 BC: The oldest European star chart. Chariot of the Sun (Denmark).
1450 BC: The Egyptians start to use sundials.
c. 1400 BC: The oldest Egyptian water clocks. The Egyptians introduce a year with 365 days, 12 months of 30 days + 5 extra birthdays for the gods Isis, Osirus, Horus, Nepthys and Set.
1302 BC: Chinese recording of a solar eclipse and recordings of a supernova.
1100 BC: Egyptian lists of stars along the ecliptic for measurement of time at night. They divided the ecliptic into 10-degree areas, decanes.
800 BC: The Chinese observe sunspots.
c. 650 BC: A star chart from Assurbanipal's library (Assyria).
c. 600 BC: The birth of Greek science. Thales assumes that it is possible to understand the Universe using simple rules. The Earth is assumed to float in a large ocean.
c. 580 BC: Anaximander. The Earth is cylindrical and isolated in space. Nothing supports it. He introduces the idea that stars and planets rest on crystal spheres.
523 BC: Written evidence of the Zodiac from the Babylonians with 12 signs.
c. 500 BC: Pythagoras of Samos proposes, for aesthetic reasons, that the Earth is spherical, the perfect form.
c.430 BC: Philolaus explains the apparent daily rotation of the heavens by saying that the Earth moves around a central fire (that mankind always turns away from). A Counter-Earth moves around the fire, along with all the other heavenly bodies.
c. 400 BC: Plato. Space is infinite and contains a finite universe with the Earth at the centre. All movements must be explained with circular movements. He perceived the visible world as a travesty of the world of ideas.
The Chinese astronomer Kan Te reports sunspots.
365 BC: Chinese observations of Jupiter’s moons.
c. 360 BC: Heraclides. The Earth rotates about its own axis. Mercury and Venus orbit the Sun, which orbits the Earth. The rest of the planets orbit the Earth.
350 BC: The Chinese astronomer Shi Shen makes a catalogue of 800 stars.
c. 340 BC: Aristotle established the circular movements as dogma in astronomy.
c. 320 BC: The Chinese astronomer Wu Xian publishes a list of 1464 stars in 284 constellations. Shortly after this, the first celestial globe is cast by Qian Luozhi.
c. 300 BC: Aristarchus argues that the Sun is the centre of the solar system. But he gains no supporters.
c. 200 BC: Eratosthenes of Alexandria measures the size of the Earth by measuring the altitude of the Sun at different locations at the same time.
Chang Heng begins to map China with a coordinate system. He uses the Mercator projection ("invented" in Europe in 1568) for his star chart.

c. 150 BC: Hipparchus, the greatest observer of antiquity, finds that Aristotle is wrong and introduces movements in epicycles (circles on circles) for the planets. He measures the distance to the Moon.
c. 65 BC: A bronze astronomical gear machine found in a Greek shipwreck in 1901 is from this time.
1 AD: Our era begins. However, it was first introduced by Dionysius Exiguus in the 6^th century.
c. 100 AD: The Chinese astronomer Zhang Heng constructs an armillary instrument that turns automatically with the heavens. It is driven by a water clock.
c. 150: Ptolemy develops his system for calculating the location of the planets in the heavens. He publishes a star catalogue with the positions of more than 1000 stars.
c. 420: Martianus Capella publishes a book in which he presents an astronomical system with the Earth at the centre of the Universe, the Moon, the Sun, Mars, Jupiter and Saturn in orbit around it and the planets Mercury and Venus in orbit around the Sun.
499: The Indian astronomer Aryabhata publishes a book in which the rotation of the heavens is explained by saying that the Earth rotates and there is a heliocentric solar system and the planets in elliptic orbits. He determines the length of the year very precisely.
642: The knowledge centre of Alexandria in Egypt is conquered by the Arabs shortly after the collapse of the Roman Empire. Greek astronomy survives in Islam (virtually none of the major Islamic astronomers are Arabs. Most are Persians). Europe enters the Dark Ages, although recent research has shown that they were not that dark after all.
721-725: The Chinese measure the size of the Earth.
c. 750: The astronomy the Arabs had taken over in Egypt flourishes in Spain.
813: Al Mamon founds a school of astronomy in Baghdad and translates Ptolemy’s works. Astronomical knowledge from around the world is collected and translated.
903: Al-Sufi draws his star charts.
c. 970: The astronomer Abu'l Wefa lays the foundations of trigonometry, a major help with astronomical calculations.
1054: Chinese astronomers see and describe a supernova in Taurus. Today it is known as the Crab Nebula.
1259: Nasir al-Din al-Tusi establishes an observatory in Maragha, Persia.
1543: Copernicus revives Aristarchus’ ideas (c. 300 BC).
1572: Tycho Brahe sees a supernova and proves that it is just as far away as the other stars.
1576: Tycho Brahe begins his important observations from the island of Hven, where he formulates his own astronomical system (click here). The English astronomer Thomas Digges presents the idea that the stars are at very different and very large distances from the Earth. He has a description of a device that indicates that he constructed a telescope (called PERSPECTIVE GLASS from the Latin perspicere, to see through). It could also have been his father Leonard who made the invention in the 1550s.
1582: Pope Gregory XIII introduces his calendar, which we still use (it was first introduced in Denmark in 1700).
1596: Fabricius discovers the variable star Mira in the Whale.
1603: Bayer publishes his star chart. He uses Greek letters to indicate the luminosity of the stars.
1604: Kepler sees a supernova.
1608: The telescope is invented. It is developed by Galileo from 1609.
1611: The first observations of sunspots with a telescope. However, they were also described in ancient Chinese sources.
1619: Kepler’s laws of planetary motion are published.
1633: Galileo’s ideas are condemned by the Catholic Church. The world’s first State observatory is established in Leiden, Holland.
1642: The world’s second State observatory is established in Rundetaarn, Denmark.
1647: Helvelius publishes the first map of the Moon.
1668: Newton builds the first reflecting telescope.
1671: The Paris observatory is established.
1675: The Royal Greenwich Observatory is established in London.
1676: Ole Rømer publishes his discovery that light has a finite speed. He uses the delay in lunar eclipses in connection with Jupiter to measure the speed.
1687: Newton’s "Principia" is published. It contains his theory of gravity.
1705: Halley predicts, based on Newton’s theory, that a comet that was seen in 1682 will pass the Earth again in 1758. It was subsequently named after him.
1725: Flamsteed publishes his star catalogue.
1728: Halley discovers that some stars have moved since antiquity. This is the proper motion of the stars.
1781: Herschel discovers the planet Uranus. Messier’s catalogue of nebulas is published.
1796: Laplace publishes his theory of the origin of the solar system.
1801: Piazzi discovers the first asteroid, Ceres.
1814: Fraunhofer finds dark lines in the Sun’s spectrum.
1838: The first measurement of the distance to a star is made by Bessel.
1845: Lord Rosse discovers the spiral structure of the galaxies.
1846: Galle discovers the planet Neptune.
1859: Kirchhoff explains the dark lines in the Sun’s spectrum.
1887: The first photographs of the sky.
1889: The first photographs of the Milky Way.
1905: Hertzsprung discovers giant and dwarf stars.
1908: A massive explosion in Siberia. Probably part of a comet colliding with the Earth.
1911: Hertzsprung and Russell find the connection between stars’ colour and luminosity.
1913: Hertzsprung is the first person to measure the distance to an object outside the Milky Way (The Small Magellanic Cloud) using the variable delta-Cepheid stars.
1915: Einstein’s General Theory of Relativity is published.
1919: Eddington "proves" that the Theory of Relativity is correct by measuring the small deflection the Sun’s gravitational field causes to light beams.
1920: Eddington begins his study of the matter between the stars. The first measurement of the diameter of stars using interferrometry.
1922: Freedman predicts, on the basis of the Theory of Relativity, that the Universe is expanding.
1924: Hubble proves that the galaxies do not belong to the Milky Way.
1925: Eddington publishes his explanation of the inner structure of the stars.
1929: Hubble discovers the ratio between the galaxies’ distance and radial speed.
1930: The planet Pluto is discovered.
1931: Jansky founds radio astronomy.
1946: Radar signals reflected by the Moon are intercepted.
1949: A 5 m telescope in Mt. Palomar is taken into use.
1955: The Jodrell Bank radio telescope is taken into use.
1957: The first satellite in orbit.
1959: The first pictures of the far side of the Moon are taken.
1962: The first X-ray source is discovered in Scorpio.
1963: The first quasar is discovered.
The first planet orbiting another star (Bernard’s star) is discovered.
The quark theory of the structure of matter is published.
1965: Cosmic background radiation is discovered.
1966: The first “soft” landing on the Moon.
1967: The first pulsar is discovered.
1969: The first person on the Moon.
1970: The first “soft” landing on Venus.
1975: A 6 m telescope is taken into use in Russia.
1976: The Viking probes land on Mars.
1977: Rings are discovered around Uranus.
1977: Voyager I and II are launched and pass the planets Jupiter and Saturn in 79-81.
1978: Charon, the moon of Pluto, is discovered.
1986: Voyager II passes Uranus and discovers 6 new moons.
Three satellites pass Halley’s Comet.
1987: The supernova SN1987A flares up. It is the first visible to the naked eye since 1604.
1988: A supernova at a distance of 5 billion light years is discovered.
1989: Voyager II passes Neptune and discovers 8 moons and 3 rings.
1990: The space telescope, Hubble, is launched.
1991: The space probe Galileo passes the asteroid Gaspera.
1992: The COBE satellite discovers irregularities in the background radiation.
The Catholic Church admits that it made a mistake when it condemned Galileo in 1633.
1994: The comet Shoemaker Levy - 9 strikes Jupiter.
1996: Mars Pathfinder begins to transmit data.
1998: The heaviest quark predicted ("Top") is found.
1999: A comparison of the luminosity and red shift of remote supernovas indicates that the Universe is expanding faster and faster.
2001: Measurements of background radiation with a high resolution show that the Universe is probably flat and that the matter we know only constitutes 5 % of its density. 25 % consists of unknown particles (called dark matter) and as much as 70 % consists of something that makes gravitational force repellent at large distances (called dark energy).
2002: It is possible to measure the speed at which gravitational force is propagated. It turns out, as anticipated in Einstein’s theory of 1915, that it happens at the speed of light. Just as when Rømer measured the speed of light in 1676, conditions in connection with the planet Jupiter are used for the measurement. The weak deflection in Jupiter’s gravitational field that occurs with radio radiation from a galaxy depends on, among other things, the speed of gravity. By measuring the deflection, it is possible to measure the speed.
2003: New measurements show that the Universe is 13.7 billion years old.
2005: The first picture of a planet that orbits a star, the star 2M1207 in the Hydra constellation, which is 230 light years away.
A Kuiper belt object that is larger than Pluto is found.