This timeline shows highlights and important events in the history of ESO. An original aim of ESO was to allow the member states to work together to build and operate advanced astronomical facilities which were beyond the capabilities of individual countries. In particular, it would allow European astronomers access to the parts of the sky best visible from the southern hemisphere, such as the centre of our own Milky Way, or our neighbour galaxies the Magellanic Clouds.

An excerpt from the preamble to the ESO Convention of 1962 reads "The Governments of the States parties to this convention [...] desirous of jointly creating an observatory equipped with powerful instruments in the Southern Hemisphere and accordingly promoting and organising co-operation in astronomical research [...]"

1950-1959
1.	21 June 1953 — A shared European Observatory is discussed for the first time at the Groningen conference in the Netherlands
2.	26 January 1954 — ESO declaration by leading astronomers from six European countries expressing the wish that a joint European observatory be established in the southern hemisphere
3.	1955 — Site testing begins in South Africa and South America, to identify the best location for the ESO observatory
1960-1969
4.	05 October 1962 — Belgium, Germany, France, the Netherlands and Sweden sign the ESO convention
5.	01 November 1962 — Otto Heckmann becomes the first Director General of ESO
6.	15 November 1963 — Chile in South America is chosen as the site for the ESO observatory
7.	17 January 1964 — the ESO Declaration is ratified, providing the financial backing of each member state
8.	October 1964 — Acquisition of the La Silla Mountain
9.	March 1966 — Dedication ceremony for the road to the summit of La Silla
10.	1966 — First Light for the 1-m ESO telescope at La Silla
11.	1967 — Denmark joins ESO (member state no. 6)
12.	1967 — Construction of ESO Headquarters in Santiago, Chile begins
13.	1968 — First Light for the Grand Prisme Objectif telescope
14.	1968 — First Light for the 1.52-m ESO telescope
15.	1969 — First Light for the 0.5-m Danish telescope
16.	25 March 1969 — Inauguration of the ESO site at La Silla by the President of the Republic of Chile, Eduardo Frei Montalva.
1970-1979
17.	1970 — Adriaan Blaauw takes over as Director General of ESO
18.	1970 — ESO's Telescope Division is the first ESO department to move into offices on the CERN premises in Geneva
19.	1971 — First Light for the 0.5-m ESO telescope
20.	1972 — First Light for the 1-m Schmidt telescope
21.	1972 — First Light for the 0.6-m Bochum telescope
22.	1975 — Lodewijk Woltjer takes over as Director General of ESO
23.	1975 — First Light of the Mid-IR Kapteyn photometer on the 1-m telescope.
24.	1976 — First Light of the Near-IR photometer on the 1-m telescope.
25.	07 November 1976 — First Light for the ESO 3.6-m telescope
26.	1979 — First Light for the 1.5-m Danish telescope
27.	1979 — First Light for the 0.9-m Dutch telescope
1980-1989
28.	1980 — ESO's European departments move into the new ESO Headquarters in Garching, Germany
29.	1980 — Start of operation of the Coudé Echelle Spectrometer (CES) on the 1.4-m Coudé Auxiliary Telescope (CAT)
30.	1980 — First Light of the near- and mid- infrared photometers on the 3.6-m telescope
31.	1981 — Switzerland joins ESO (member state no. 7)
32.	1982 — First Light of the near- and mid- infrared photometers on the 1-m telescope
33.	24 May 1982 — Italy joins ESO (member state no. 8)
34.	1983 — First Light for the 2.2-m Max Planck Society (MPG)/ESO Telescope
35.	March 1984 — The Space Telescope European Coordinating Facility — the European home for Hubble — opens within ESO as a collaboration with the European Space Agency.
36.	1984 — Start of operation of the Cassegrain Echelle Spectrograph (CASPEC) at the ESO 3.6-m telescope
37.	November 1984 — First Light of the F/35 chopping secondary system and the infrared photometers on the 3.6-m telescope
38.	October 1985 — First Light of the Lyon Specklegraph on the 3.6-m telescope
39.	November 1985 — First Light of IRSPEC on the 3.6-m telescope
40.	1987 — First Light for the 15-m Swedish-ESO Sub-millimetre Telescope (SEST)
41.	March 1987 — First Light of the F/35 photometers with MPIA on the 2.2-m telescope
42.	01 December 1987 — Decision is taken by the ESO Council to build the Very Large Telescope (VLT)
43.	1988 — Harry van der Laan takes over as Director General of ESO
44.	July 1988 — First Light of IRAC on the 2.2-m telescope
45.	23 March 1989 — First light of the New Technology Telescope (NTT)
46.	11 May 1989 — First Light of the second ESO Faint Object Spectrograph and Camera (EFOSC2) instrument on the NTT telescope.
1990-1999
47.	April 1990 — First Light of the COME-ON Instrument on the 3.6-m ESO telescope
48.	November 1990 — Start of operation of the ESO Multi-Mode Instrument (EMMI) on the NTT
49.	01 December 1990 — Paranal site selected for the VLT
50.	May 1992 — First Light of the IRAC instrument on the 2.2-m telescope
51.	July 1992 — First Light of the Thermal Infrared MultiMode Instrument (TIMMI) on the 3.6-m ESO telescope
52.	December 1992 — First Light of the COME-ON+ instrument on the 3.6-m telescope
53.	1992 — Riccardo Giacconi takes over as Director General of ESO
54.	1995 — Site testing for the future Atacama Large Millimeter/submillimeter Array (ALMA) takes place in Chile together with National Radio Astronomy Observatory and National Astronomical Observatory of Japan
55.	18 April 1995 — New agreement between Chilean Government and ESO
56.	05 September 1996 — The Chilean Senate ratifies the new agreement with ESO
57.	01 December 1996 — Paranal Foundation Ceremony
58.	06 December 1997 — First Light for the Son OF ISAAC instrument (SOFI) on the NTT
59.	1998 — First Light for the 1.2-m Swiss Euler telescope at La Silla
60.	February 1998 — First Light for the second Superb-Seeing Imager (SuSI2) on the NTT
61.	25 May 1998 — First light for the VLT's first Unit Telescope (UT1), Antu
62.	15 September 1998 — First Light for the first visual and near UV FOcal Reducer and low dispersion Spectrograph (FORS1) on the VLT's UT1, Antu
63.	06 October 1998 — First Light of the Fiber-fed Extended Range Optical Spectrograph (FEROS) on the ESO 1.52-m telescope
64.	16 November 1998 — First Light of the Infrared Spectrometer And Array Camera (ISAAC) instrument on VLT UT1, Antu
65.	15 January 1999 — First Light with the 67-Million-Pixel Wide Field Imager (WFI) Camera on the 2.2-m telescope
66.	01 March 1999 — First Light for the VLT's second Unit Telescope (UT2), Kueyen
67.	05 March 1999 — Official inauguration of Paranal Observatory
68.	April 1999 — Start of regular science operations at Paranal
69.	1 September 1999 — Catherine Cesarsky takes over as Director General of ESO
70.	27 September 1999 — First light for the Ultraviolet Visual Echelle Spectrograph (UVES) on VLT's UT2, Kueyen
71.	29 October 1999 — First light for the second visual and near UV FOcal Reducer and low dispersion Spectrograph (FORS2) at VLT's UT2, Kueyen
2000-2009
72.	27 June 2000 — Portugal joins ESO (member state no. 9)
73.	26 January 2000 — First Light for the VLT's third Unit Telescope (UT3), Melipal
74.	04 September 2000 — First Light for the VLT's fourth Unit Telescope (UT4), Yepun
75.	October 2000 — First Light of the second Thermal Infrared MultiMode Instrument (TIMMI2) on the 3.6-m telescope
76.	17 March 2001 - First Light for the Very Large Telescope Interferometer (VLTI)
77.	April 2001 — Resolution for the Atacama Large Millimeter/submillimeter Array (ALMA) between Europe, North America and Japan
78.	25 November 2001 — First Light for the combined NAOS-CONICA instrument (NACO) on VLT's UT4 Yepun
79.	26 February 2002 — First light of the VIsible Multi-Object Spectrograph (VIMOS) on the VLT's UT3, Melipal
80.	01 July 2002 — the United Kingdom joins ESO (member state no. 10)
81.	October 2002 — The 0.6-metre Rapid Eye Mount (REM) Telescope starts operations at La Silla.
82.	24 October 2002 — First Light of the Fibre-fed Extended Range Optical Spectrograph (FEROS) on the 2.2-m telescope
83.	15 December 2002 — First Light of the MID-infrared Interferometric instrument (MIDI) on the VLTI
84.	February 2003 — First light of the Fibre Large Array Multi Element Spectrograph (FLAMES) on VLT's UT2, Kueyen
85.	February 2003 — ESO and the US National Science Foundation sign a Bilateral Agreement on the Atacama Large Millimeter/submillimeter Array (ALMA)
86.	11 February 2003 — First Light of the High Accuracy Radial Velocity Planet Searcher (HARPS) at ESO's 3.6-m telescope at the La Silla Observatory
87.	18 April 2003 — First Light of the MACAO-VLTI facility
88.	November 2003 — Groundbreaking ceremony at the site of Atacama Large Millimeter/submillimeter Array (ALMA)
89.	January 2004 — The robotic TAROT-South Telescope is starting work at La Silla.
90.	30 January 2004 — First Light for the first Auxiliary Telescope (AT1)
91.	March 2004 — First fringes of the Astronomical Multi-BEam combineR (AMBER) on the VLTI
92.	30 April 2004 — First Light for the VLT Imager and Spectrometer in the InfraRed (VISIR) on VLT's UT3, Melipal
93.	01 July 2004 — Finland joins ESO (member state no. 11)
94.	09 July 2004 — First Light for the Spectrograph for INtegral Field Observation in the Near-Infrared (SINFONI) on the VLT's UT4, Yepun
95.	September 2004 — Agreement is reached between ESO, NSF and NINS, concerning the construction of the Atacama Large Millimeter / submillimeter Array (ALMA)
96.	02 February 2005 — First Light for the second Auxiliary Telescope (AT2)
97.	July 2005 — First Light for the sub-millimetre Atacama Pathfinder Experiment (APEX)
98.	01 November 2005 — First Light for the third Auxiliary Telescope (AT3)
99.	December 2005 — ESO signs the European contract for the production of up to 32 ALMA antennas. This is the largest ever contract for industrial work on a ground-based astronomy project.
100.	28 January 2006 — First Light of the VLT Laser Guide Star, on the VLT's UT4, Yepun
101.	04 June 2006 — First light for the CRyogenic high-resolution InfraRed Echelle Spectrograph (CRIRES) at VLT's UT1
102.	01 July 2006 — Spain joins ESO (member state no. 12)
103.	11 December 2006 — ESO Council agree to proceed with studies for the European Extremely Large Telescope (E-ELT)
104.	15 December 2006 — First Light for the fourth Auxiliary Telescope (AT4)
105.	01 January 2007 — Czech Republic joins ESO (member state no. 13)
106.	25 March 2007 — First Light for the Multi-Conjugate Adaptive Optics Demonstrator (MAD) at the Visitor Focus of Melipal
107.	06 July 2007 — First Light of the Gamma-Ray burst Optical/Near-infrared Detector (GROND) on the 2.2-m telescope
108.	August 2007 — First Light for the LArge BOlometer CAmera (LABOCA) instrument on APEX
109.	22 August 2007 — First Light for the High Acuity, Wide field K-band Imaging (HAWK-I) instrument on VLT's UT4, Yepun
110.	01 September 2007 — Tim de Zeeuw takes over as Director General of ESO
111.	March 2008 — Filming of scenes from the 22nd James Bond movie Quantum of Solace at ESO's Paranal Observatory
112.	01 July 2008 — Austria joins ESO (member state no. 14)
113.	08 September 2008 — First Light for the Phase Referenced Imaging and Microarcsecond Astrometry (PRIMA) instrument on the VLTI
114.	06 October 2008 — First Light for the Submillimeter APEX Bolometer Camera (SABOCA) instrument on APEX
115.	November 2008 — First Light for X-shooter on the VLT
116.	December 2008 — ALMA observatory is equipped with its first antenna
117.	06 May 2009 — The first two ALMA antennas are successfully linked
118.	17 Sep 2009 — First ALMA antenna arrives at 5000-m altitude Chajnantor site
119.	21 Oct 2009 — First two ALMA antennas are successfully linked at 5000-m altitude Chajnantor site
120.	25 November 2009 — Phase Closure of ALMA (3 antennas)
121.	11 December 2009 — VISTA, the Pioneering New Survey Telescope,Starts Work
122.	26 April 2010 — E-ELT site chosen
123.	June 2010 — First light of the TRAPPIST telescope at La Silla.