The History Of Astronomy

To give every date of importance in the history of astronomy would be a mammoth undertaking. What I have therefore tried to do is to make a judicious selection, separating out purely space-research advances and discoveries.

It is impossible to say just when astronomy began, but even the earliest men capable of coherent thought must have paid attention to the various objects to be seen in the sky, so that it may be fair to say that astronomy is as old as Homo sapiens. Among the earliest peoples to make systematic studies of the stars were the Mesopotamians, the Egyptians and the Chinese, all of whom drew up constellation patterns. (There have also been suggestions that the constellations we use as a basis today were first worked out in Crete, but this is speculation only.) It seems that some constellation-systems date back to 3000 BC, probably earlier, but of course all dates in these very ancient times are uncertain.

The first essential among ancient civilizations was the compilation of a good calendar. Probably the first reasonably accurate value of the length of the year (365 days) was given by the Egyptians. (The first recorded monarch of all Egypt was Menes, who seems to have reigned around 3100 BC; he was eventually killed by a hippopotamus - possibly the only sovereign ever to have met with such a fate!) They paid great attention to the star Sirius (Sothis), because its 'heliacal rising', or date when it could first be seen in the dawn sky, gave a reliable clue to the time of the annual flooding of the Nile, upon which the Egyptian economy depended. The Pyramids are, of course, astronomically aligned, and arguments about the methods by which they were constructed still rage as fiercely as ever.

Obviously the Egyptians had no idea of the scale of the universe, and they believed the flat Earth to be all important. So too did the Chinese, who also made observations. It has been maintained that a conjunction of the five naked-eye planets recorded during the reign of the Emperor Chuan Hsu refers to either 2449 or 2446 BC. There is also the legend of the Court Astronomers, Hsi and Ho, who were executed in 2136 BC (or, according to some authorities, 2159 BC) for their failure to predict a total solar eclipse; since the Chinese believed eclipses to be due to attacks on the Sun by a hungry dragon, this was clearly a matter of extreme importance! However, this legend is discounted by modern scholars.

The earliest data collectors were the Assyrians; all students of ancient history know of the Library of Ashurbanipal (668-626 BC). This included the 'Venus Tablet', discovered by Sir Henry Layard and deciphered in 1911 by F. X. Kugler. It claims that when Venus appears, 'rains will be in the heavens'; when it returns after an absence of three months 'hostility will be in the land; the crops will prosper'. Early attempts at drawing up tables of the movements of the Moon and planets may well date from pre-Greek times, largely for astrological reasons; until relatively modern times astrology was regarded as a true science, and all the ancient astronomers (even Ptolemy) were also astrologers.

Babylonian astronomy continued well into Greek times, and some of the astronomers, such as Naburiannu (about 500 BC) and Kidinnu (about 380 BC) may have made great advances; but we know relatively little about them, and reliable dating begins only with the rise of Greek science.

Little progress was made in the following centuries, though there were some interesting Indian writings (Aryabhata, 5th century AD), and in 570 AD Isidorus, Bishop of Seville, was the first to draw a definite distinction between astronomy and astrology. The revival of astronomy was due to the Arabs. In 813 Al-Ma'mun founded the Baghdad school of astronomy, and various star catalogues were drawn up, the most notable being that of Al-Sufi (born about 903). During this period two supernova were observed by Chinese astronomers; the star of 1006 (in Lupus) and 1054 (in Taurus, the remnant of which is today seen as the Crab Nebula).

The improved 'Alphonsine Tables' of planetary motions were published in 1270 by order of Alphonso X

of Castile. In 1433 Uliigh Beigh set up an elaborate observatory at Samarkand, but unfortunately he was a firm believer in astrology, and was told that his eldest son Abdallatif was destined to kill him. He therefore banished his son, who duly returned at the head of an army and had UlUgh Beigh murdered. This marked the end of the Arab school of astronomy, and subsequent developments were mainly European. Some of the important dates in the history of astronomy are as follows:

1543 Publication of Copernicus' book De Revolutionibus Orbium Cwlestium. This sparked off the 'Copernican revolution' which was not really complete until the publication of Newton's Principia in 1687. 1545-59 First telescope built by Leonard Digges? 1572 Tycho Brahe observed the supernova in Cassiopeia. 1576-96 Tycho worked at Hven, drawing up the best star catalogue of pre-telescopic times. 1600 Giordano Bruno burned at the stake in Rome, partly because of his defence of the theory that the Earth revolves round the Sun.

1603 Publication of Johann Bayer's star catalogue, Uranometria.

1604 Appearance of the last supernova to be observed in our Galaxy (Kepler's Star, in Ophiuchus).

1608 Telescope built by H. Lippershey, in Holland.

1609 First telescopic lunar map, drawn by Thomas Harriot. Serious telescopic work begun by Galileo, who made a series of spectacular discoveries in 1609-10 (phases of Venus, satellites of Jupiter, stellar nature of the Milky Way). Publication of Kepler's first two Laws of Planetary Motion. 1618 Publication of Kepler's third Law of Planetary Motion. 1627 Publication by Kepler of improved planetary tables (the Rudolphine Tables).

1631 First transit of Mercury observed by Gassendi (following Kepler's prediction of it).

1632 Publication of Galileo's Dialogue, which amounted to a defence of the Copernican system. In 1633 he was condemned by the Inquisition in Rome, and was forced into a completely hollow recantation. Founding of the first official observatory (the tower observatory at Leiden, Holland).

1637 Founding of the first national observatory (Copenhagen, Denmark).

1638 Identification of the first variable star (Mira Ceti, by Phocylides Holwarda in Holland).

1639 First transit of Venus observed (by Horrocks and Crabtree, in England, following Horrocks' prediction of it). 1647 Publication of Hevelius' map of the Moon.

1651 Publication of Riccioli's map of the Moon, introducing the modern-type lunar nomenclature.

1655 Discovery of Saturn's main satellite, Titan, by C. Huygens, who announced the correct explanation of Saturn's ring system in the same year.

1656 Founding of the second Copenhagen Observatory. 1659 Markings on Mars seen for the first time (by Huygens). 1663 First description of the principle of the reflecting telescope, by the Scottish mathematician James Gregory.

1665 Newton's pioneering experiments on light and gravitation, carried out at Woolsthorpe in Lincolnshire while Cambridge University was temporarily closed because of the Plague.

1666 First observation of the Martian polar caps, by G. D. Cassini.

1667 Founding of the Paris Observatory, with Cassini as Director. (It was virtually in action by 1671).

1668 First reflector made, by Newton. (This is the probable date. It was presented to the Royal Society in 1671, and still exists).

1675 Founding of the Royal Greenwich Observatory. Velocity of light measured, by O. R0mer (Denmark).

1676 First serious attempt at cataloguing the southern stars, by Edmond Halley from St Helena.

1685 First astronomical observations made from South Africa (Father Guy Tachard, at the Cape). 1689 Publication of Newton's Principia, finally proving the truth of the theory that the Sun is the centre of the Solar System.

1704 Publication of Newton's other major work, Opticks.

1705 Prediction of the return of a comet, by Halley (for 1758).

1723 Construction of the first really good reflecting telescope (a 6 in, by Hadley).

1725 Publication of the final version of the star catalogue by Flamsteed, drawn up at Greenwich. (Publication was posthumous).

1728 Discovery of the aberration of light, by James Bradley.

1750 First extensive catalogue of the southern stars, by Lacaille at the Cape. (His observations extended from 1750 to 1752). Wright's theory of the origin of the Solar System. 1758 First observation of a comet at a predicted return (Halley's Comet, discovered on 25 December by Palitzsch. Perihelion occurred in 1759). Principle of the achromatic refractor discovered by Dollond. (Previously described, by Chester Moor Hall in 1729, but his basic theory was erroneous, and his discovery had been forgotten.)

1761 Discovery of the atmosphere of Venus, during the transit of that year, by M. V. Lomonosov in Russia.

1762 Completion of a new star catalogue by James Bradley; it contained the measured positions of 60 000 stars.

1767 Founding of the Nautical Almanac, by Nevil Maskelyne.

1769 Observations of the transit of Venus made from many stations all over the world, including Tahiti (the expedition commanded by James Cook).

1774 First recorded astronomical observation by William Herschel.

1779 Founding of Johann Schroter's private observatory at Lilienthal, near Bremen.

1781 Publication of Charles Messier's catalogue of clusters and nebula. Discovery of the planet Uranus, by William Herschel.

1783 First explanation of the variations of Algol, by Goodricke. (Algol's variability had been discovered by Montanari in 1669.)

1784 First Cepheid variable discovered; 8 Cephei itself, by Goodricke.

1786 First reasonably correct description of the shape of the Galaxy given, by William Herschel. 1789 Completion ofHerschel's great reflector, with a mirror 49 in (124.5 cm) in diameter and a focal length of 40 ft (12.2 m).

1796 Publication of Laplace's 'Nebular Hypothesis' of the origin of the Solar System.

1799 Great Leonid meteor shower, observed by W. Humboldt.

1800 Infra-red radiation from the Sun detected by W. Herschel.

1801 First asteroid discovered (Ceres, by Piazzi at Palermo).

1802 Second asteroid discovered (Pallas, by Olbers). Existence of binary star systems established by W. Herschel.

Dark lines in the solar spectrum observed by W. H. Wollas-ton.

1804 Third asteroid discovered (Juno, by Harding). 1807 Fourth asteroid discovered (Vesta, by Olbers). 1814-18 Founding of the Calton Hill Observatory, Edinburgh.

1815 Fraunhofer's first detailed map of the solar spectrum (324 lines).

1820 Foundation of the Royal Astronomical Society.

1821 Arrival of F. Fallows at the Cape, as Director of the first observatory in South Africa. Founding of the Paramatta Observatory by Sir Thomas Brisbane, Governor of New South Wales. (This was the first Australian observatory. It was dismantled in 1847).

1822 First calculated return of a short-period comet (Encke's, recovered by Ruimker at Paramatta).

1824 First telescope to be mounted equatorially, with clock drive (the Dorpat refractor, made by Fraunhofer). 1827 First calculation of the orbit of a binary star (f Ursa Majoris, by Savary).

1829 Completion of the Royal Observatory at the Cape. 1834-8 First really exhaustive survey of the southern stars, carried out by John Herschel at Feldhausen (Cape). 1835 Second predicted return of Halley's Comet.

1837 Publication of the famous lunar map by Beer and Madler. Publication of the first good catalogue of double stars (W. Struve's Mensurw Micrometricw).

1838 First announcement of the distance of a star (61 Cygni, by F. W. Bessel).

1839 Pulkovo Observatory completed.

1840 First attempt to photograph the Moon (by J. W. Draper).

1842 Important total solar eclipse, from which it was inferred that the corona and prominences are solar rather than lunar. First attempt to photograph totality (by Majocci), though he recorded only the partial phase.

1843 First daguerreotype of the solar spectrum obtained (by Draper).

1844 Founding of the Harvard College Observatory (first official observatory in the United States). The 15 in refractor was installed in 1847.

1845 Completion of Lord Rosse's 72 in reflector at Birr Castle, and the discovery with it of the spiral forms of galaxies ('spiral nebula'). Daguerreotype of the Sun taken by Fizeau and Foucault, in France. Discovery of the fifth asteroid (Astraa, by Hencke).

1846 Discovery of Neptune, by Galle and D'Arrest at Berlin, from the prediction by Le Verrier. The large satellite of Neptune (Triton) was discovered by W. Lassell in the same year.

1850 First photograph of a star (Vega, from Harvard College Observatory). Castor was also photographed, and the image was extended, though the two components were not shown separately. Discovery of Saturn's Crepe Ring (Bond, at Harvard).

1851 First photograph of a total solar eclipse (by Berkowski). Schwabe's discovery of the solar cycle established by W. Humboldt.

1857 Clerk Maxwell proved that Saturn's rings must be composed of discrete particles. Founding of the Sydney Observatory. First good photograph of a double star (Mizar, with Alcor, by Bond, Whipple and Black).

1858 First photograph of a comet (Donati's, photographed by Usherwood).

1859 Explanation of the absorption lines in the solar spectrum given by Kirchhoff and Bunsen. Discovery of the Sun's differential rotation (by Carrington).

1860 Total solar eclipse. Final demonstration that the corona and prominences are solar rather than lunar. 1861-2 Publication of Kirchhoff's map of the solar spectrum.

1862 Construction of the first great refractors, including the Newall 25 in made by Cooke. (It was for many years at Cambridge, and is now in Athens.) Discovery of the Companion of Sirius (by Clark, at Washington). Completion of the Bonner Durchmusterung.

1863 Secchi's classification of stellar spectra published.

1864 Huggins' first results in his studies of stellar spectra. First spectroscopic examination of a comet (Tempel's, by Donati). First spectroscopic proof that 'nebula' aregaseous (by Huggins). Founding of the Melbourne Observatory. (The 'Great Melbourne Reflector' completed 1869). 1866 Association between comets and meteors established (by G. V. Schiaparelli). Great Leonid meteor shower. Announcement by J. Schmidt of an alteration in the lunar crater Linne. (Though the reality of change is now discounted, regular lunar observation dates from this time.)

1867 Studies of 'Wolf-Rayet' stars by Wolf and Rayet, at Paris.

1868 First description of the method of observing the solar prominences at times of non-eclipse (independently by Janssen and Lockyer). Publication of a detailed map of the solar spectrum, by A. Angstrom.

1870 First photograph of a solar prominence (by C. Young). 1872 First photograph of the spectrum of a star (Vega, by H. Draper).

1874 Transit of Venus; solar parallax redetermined. (Another transit occurred in 1882, but the overall results were disappointing). Founding of observatories at Meudon (France) and Adelaide (Australia).

1876 First use of dry gelatine plates in stellar photography; spectrum of Vega photographed by Huggins.

1877 Discovery of the two satellites of Mars (by Hall, at Washington). Observations of the 'canals' of Mars (by Schiaparelli, at Milan).

1878 Publication of the elaborate lunar map by J. Schmidt (from Athens). Completion of the Potsdam Astrophysical Observatory.

1879 Founding of the Brisbane Observatory.

1880 First good photograph of a gaseous nebula (M.42, by Draper).

1882 Gill's classic photograph of the Great Comet of 1882, showing so many stars that the idea of stellar cataloguing by photography was born.

1885 Founding of the Tokyo Observatory. (An earlier naval observatory in Tokyo had been established in 1874.) Supernova in M.31, the Andromeda Galaxy (S Andromeda). This was the only recorded extragalactic supernova to reach the fringe of naked-eye visibility until 1987.

1886 Photograph of M.31 (the Andromeda Galaxy) by Roberts, showing spiral structure. (A better photograph was obtained by him in 1888.)

1887 Completion of the Lick 36 in refractor.

1888 Publication of J. L. E. Dreyer's New General Catalogue of clusters and nebula. Vogel's first spectrographic measurements of the radial velocities of stars.

1889 Spectrum of M.31 photographed by J. Scheiner, from Potsdam. Discovery at Harvard of the first spectroscopic binaries (Z UrsaMajoris and i Auriga). First photographs of the Milky Way taken (by E. E. Barnard).

1890 Foundation of the British Astronomical Association. Unsuccessful attempts to detect radio waves from the Sun, by Edison. (Sir Oliver Lodge was equally unsuccessful in 1896.) Publication of the Draper Catalogue of stellar spectra.

1891 Completion of the Arequipa southern station of Harvard College Observatory. Spectroheliograph invented by G. E. Hale. First photographic discovery of an asteroid (by Max Wolf, from Heidelberg).

1892 First photographic discovery of a comet (by E. E. Barnard).

1893 Completion of the 28 in Greenwich refractor.

1894 Founding of the Lowell Observatory at Flagstaff, in Arizona.

1896 Publication of the first lunar photographic atlas (Lick), Founding of the Perth Observatory. Completion of the Meudon 33 in (83 cm) refractor. Completion of the new Royal Observatory at Blackford Hill, Edinburgh. Discovery of the predicted Companion to Procyon (by Schaeberle).

1897 Completion of the Yerkes Observatory.

1898 Discovery of the first asteroid to come well within the orbit of Mars (433 Eros, discovered by Witt at Berlin).

1899 Spectrum of the Andromeda Galaxy (M.31) photographed by Schelner.

1900 Publication of Burnham's catalogue of 1290 double stars. Horizontal refractor, of 49 in aperture, focal length 197 ft (60 m), shown at the Paris Exhibition. (It was never used for astronomical research.)

1905 Founding of the Mount Wilson Observatory (California).

1908 Giant and dwarf stellar divisions described by E. Hertzsprung (Denmark). Completion of the Mount Wilson 60 in reflector. Fall of the Siberian meteorite.

1912 Studies of short-period variables in the Small Magellanic Cloud, by Miss H. Leavitt, leading on to the period-luminosity law of Cepheids.

1913 Founding of the Dominion Astrophysical Observatory, Victoria (British Columbia). H. N. Russell's theory of stellar evolution announced.

1915 W. S. Adams' studies of Sirius B, leading to the identification of White Dwarf stars.

1917 Completion of the 100 in Hooker reflector at Mount Wilson (the largest until 1948).

1918 Studies by H. Shapley leading him to the first accurate estimate of the size of the Galaxy.

1919 Publication of Barnard's catalogue of dark nebula.

1920 The Red Shifts in the spectra of galaxies announced by V. M. Slipher.

1923 Proof given (by E. Hubble) that the galaxies are true independent systems rather than parts of our Milky Way system. Invention of the spectrohelioscope, by Hale. 1925 Establishment of the Yale Observatory at Johannesburg. (It was finally dismantled in 1952, its work done.) 1927 Completion of the Boyden Observatory at Bloem-fontein, South Africa.

1930 Discovery of Pluto, by Clyde Tombaugh at Flagstaff. Invention of the Schmidt camera, by Bernhard Schmidt (Estonia).

1931 First experiments by K. Jansky at Holmdel, New Jersey, with an improvised aerial, leading on to the founding of radio astronomy. Jansky published his first results in 1932, and in 1933 found that the radio emission definitely came from the Milky Way.

1932 Discovery of carbon dioxide in the atmosphere of Venus (by T. Dunham).

1933-5 Completion of the David Dunlap Observatory near Toronto (Canada).

1937 First intentional radio telescope built (by Grote Reber); it was a 'dish' 31 ft (9.4 m) in diameter.

1938 New (and correct) theory of stellar energy proposed by H. Bethe and, independently, by C. von Weizsacker. 1942 Solar radio emission detected by M. H. Hey and his colleagues (27-28 February). The emission had previously been attributed to intentional jamming by the Germans!

1944 Suggestion, by H. C. van de Hulst, that interstellar hydrogen must emit radio waves at a wavelength of 21.2 cm.

1945 Thermal radiation from the Moon detected at radio wavelengths (by R. H. Dicke).

1945-6 First radar contact with the Moon, by Z. Bay (Hungary) and independently by the US Army Signal Corps Laboratory.

1946 Work at Jodrell Bank begun (radar reflections from the Giacobinid meteor trails, 10 October). Beginning of radio astronomy in Australia (solar work by a team led by

E. G. Bowen). Identification of the radio source Cygnus A by Hey, Parsons and Phillips.

1947-8 Photoelectric observations of variable stars in the infra-red carried out by Lenouvel, using a Lallemand electronic telescope.

1948 Completion of the 200 in Hale reflector at Palomar (USA). Identification of the radio source Cassiopeia A, by M. Ryle and F. G. Smith.

1949 Identification of further radio sources; Taurus A (the Crab Nebula), Virgo A (M.87), and Centaurus A (NGC 5128). These were the first radio sources beyond the Solar System to be identified with optical objects.

1950 M.31 (the Andromeda Galaxy) detected at radio wavelengths by M. Ryle, F. G. Smith and B. Elsmore. Funds for the building of the great Jodrell Bank radio telescope obtained by Sir Bernard Lovell.

1951 Discovery by H. Ewen and E. Purcell of the 21 cm emission from interstellar hydrogen thus confirming van de Hulst's prediction. Optical identification of Cygnus A and Cassiopeia A (by Baade and Minkowski, using the Palomar reflector, from the positions given by Smith).

1952 W. Baade's announcement of an error in the Cepheid luminosity scale, showing that the galaxies are about twice as remote as had been previously thought. Electronic images of Saturn and 0 Orionis obtained by Lallemand and Duchesne (Paris). Tycho's supernova of 1572 identified at radio wavelengths by Hanbury Brown and Hazard.

1953 I. Shklovskii explains the radio emission from the Crab Nebula as being due to synchroton radiation.

1955 Completion of the 250 ft radio 'dish' at Jodrell Bank. First detection of radio emissions from Jupiter (by Burke and Franklin). Construction of a radio interferometer by M. Ryle, and also the completion of the 2nd Cambridge catalogue of radio sources. (The 3rd Cambridge catalogue was completed in 1959).

1958 Observations of a red event in the lunar crater Alphonsus, by N. A. Kozyrev (Crimean Astrophysical Observatory, USSR). Venus detected at radio wavelengths (by Mayer).

1959 Radar contact with the Sun (Eshleman, at the Stanford Research Institute, USA).

1960 Aperture synthesis method developed by M. Ryle and A. Hewish.

1961 Completion of the Parkes radio telescope, 330 km west of Sydney.

1962 Thermal radio emission detected from Mercury, by Howard, Barrett and Haddock, using the 85 ft radio telescope at Michigan. First radar contact with Mercury (Kotelnikov, USSR). First X-ray source detected (in Scorpius). Sugar Grove fiasco; the US attempt to build a 600 ft fully steerable radio 'dish'. Work had begun in 1959, and when discontinued had cost $ 96 000 000.

1963 Announcement by P. van de Kamp, of a planet attending Barnard's Star (later found to be spurious). Identification of quasars (M. Schmidt, Palomar). 1965-6 Identification of the 3 °K microwave radiation, as a result of theoretical work by Dicke and experiments by Penzias and Wilson.

1967 Completion of the 98 in Isaac Newton reflector at Herstmonceux. Identification of the first pulsar, CP 1919, by Jocelyn Bell at Cambridge.

1968 Identification of the Vela pulsar (Large, Vaughan and Mills).

1969 First optical identification of a pulsar; the pulsar in the Crab Nebula by Cocke, Taylor and Disney at the Steward Observatory, USA.

1970 Completion of the 100 m radio 'dish' at Bonn (Germany). Completion of the large reflectors for Kitt Peak (Arizona) and Cerro Tololo (Chile); each 158 in (401 cm) aperture. First large reflector to be erected on Mauna Kea, Hawaii; an 88 in (224 cm).

1973 Opening of the Sutherland station of the South African Astronomical Observatories.

1974 Completion of the 153 in (389 cm) reflector at the Siding Spring Observatory, Australia.

1976 Completion of the 236 in (600 cm) reflector at Mount Semirodriki (USSR).

1977 Optical identification of the Vela pulsar (at Siding Spring). Discovery of Chiron (by C. Kowal, USA). Discovery of the rings of Uranus.

1978 Completion of the new Russian underground neutrino telescope. Discovery of Charon, the satellite of Pluto (J. Christy, USA). Discovery of the first satellite of an asteroid (Herculina). Rings of Uranus recorded from Earth (Matthews, Neugebauer, Nicholson). Discovery of X-rays from SS Cygni (HEAO 1).

1979 Official opening of the observatory at La Palma. Pluto and Charon recorded separately (Bonneau and Foy, Mauna Kea, thereby confirming Charon's independent existence). First comet observed to hit the Sun.

1980 Discovery of the first scintar (SS 433).

1981 Five asteroids contacted by radar from Arecibo, including two Apollos (Apollo itself, and Quetzalcoatl).

1982 Discovery of the remote quasar PKS 2000-330 (Wright and Launcey, Parkes). Recovery of Halley's Comet.

1983 Discovery of the fastest-vibrating pulsar, PKS 1937+215 in Vulpecula: period 1.557 806449 022 milliseconds - twenty times shorter than the Crab pulsar. It spins 642 times per second.

1984 Isaac Newton Telescope installed on La Palma.

1986 Return of Halley's Comet.

1987 Completion of the William Herschel telescope at La Palma. Completion of the James Clerk Maxwell telescope on Mauna Kea. Supernova seen in the Large Cloud of Magellan.

1988 Completion of the Australia Telescope (radio astronomy network). Collapse of the Green Bank radio telescope.

1989 NTT (New Technology Telescope) brought into action at the European Southern Observatory, La Silla. Identification of the 'Great Wall' of galaxies.

1990 First brown dwarf identified by M. Hawkins. First surface details on a star (Betelgeux) detected from La Palma Observatory. First light on the Keck Telescope (Mauna Kea). White spot discovered on Saturn (24 September). End of the Pluto-Charon mutual phenomena (24 September). Sir Francis Graham-Smith retires as Astronomer Royal.

1991 Professor Arnold Wolfendale appointed Astronomer Royal. First really reliable measurement made of the distance of the Large Magellanic Cloud. Outburst of Halley's Comet (12 February). Fall of the Glatton Meteorite (5 May). First space image obtained of an asteroid, Gaspra (13 November).

1992 Completion of the Keck I telescope on Mauna Kea, Hawaii. Discovery of the first Kuiper Belt object (Jewitt and Luu, 31 August).

1993 Discovery of the first asteroidal satellite, Dactyl (25 August). Start of SETI, the Search for Extra-terrestrial

Intelligence (12 October). Galileo exonerated of heresy by the Pope (30 October). (Galileo had been condemned for heresy on 22 June 1633!)

1994 Hooker telescope on Mt Wilson reopened. SETI cancelled by US Congress (14 March). Impact of Comet Shoemaker-Levy 9 on Jupiter (17-22 July). Discovery of the nearest galaxy, 80 000 light-years away (Ibata, 4 August).

1995 Professor Sir Martin Rees succeeds Sir Arnold Wolfendale as Astronomer Royal (January). First light on the VATT (Mount Graham) (July). Mayor and Queloz announce the discovery of a planet round 51 Pegasi (October). First maps of Vesta (HST) (November). Galileo probe impacts Jupiter (December 7).

1996 Hipparcos catalogue completed (February). HST sends back images of star-forming regions in M.16 (Eagle Nebula) (February). First surface details recorded on Pluto (HST) (March). Dedication of Keck II Telescope (May 8).

1997 First images of Mars from Pathfinder (July 4). Dedication of Hobby-Eberly Telescope (October 8).

1998 First light on Antu (first mirror of VLT) (May). Closure of the Royal Greenwich Observatory (October 31).

1999 First images released from Suburu telescope (January). First light on Kueyen (second mirror of VLT) (March). New mirror installed at the Rosse telescope, Birr (June 22). Inauguration of the Gemini North telescope on Mauna Kea (June 25-27). Total solar eclipse seen from Cornwall and Devon (August 11). Brilliant Leonid meteor shower (November 18). December 1999 reopening of the Rosse Telescope at Birr. First visual confirmation of an extra-solar planet (orbiting t Bootis) (December).

2000 First light on Melipal (3rd mirror of VLT) (January 26). Asteroid Eros mapped from close range by the Shoemaker probe (February). First detection of an isolated black hole.

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