European Southern Observatory

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The European Southern Observatory (ESO; formally the European Organisation for Astronomical Research in the Southern Hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...

. Observatoire européen austral, in French
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...

 ) is an intergovernmental research organisation for astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

, supported by fifteen countries. Created in 1962, ESO has provided astronomers with state-of-the-art research facilities and access to the southern sky. The organisation employs around 730 staff members and receives annual member state contributions of approximately 143 million Euros.

ESO has built and operated some of the largest and most technologically advanced telescope
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...

s in the world. These include the New Technology Telescope
New Technology Telescope
The New Technology Telescope or NTT is an Alt-Az, 3.58-metre Richey-Chretien telescope part of the European Southern Observatory and began operations in 1989. It is located in Chile at the La Silla Observatory and was an early pioneer on the use of active optics...

 (NTT) that pioneered active optics
Active optics
Active optics is a technology used with reflecting telescopes developed in the 1980s, which actively shapes a telescope's mirrors to prevent deformation due to external influences such as wind, temperature, mechanical stress...

 technology, and the Very Large Telescope
Very Large Telescope
The Very Large Telescope is a telescope operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. The VLT consists of four individual telescopes, each with a primary mirror 8.2m across, which are generally used separately but can be used together to...

 (VLT), consisting of four 8-metre class telescopes and four 1.8-metre Auxiliary Telescopes. Currently on-going ESO projects include the Atacama Large Millimeter Array
Atacama Large Millimeter Array
The Atacama Large Millimeter/sub-millimeter Array is an array of radio telescopes in the Atacama desert of northern Chile. Since a high and dry site is crucial to millimeter wavelength operations, the array is being constructed on the Chajnantor plateau at 5000 metres altitude...

 (ALMA) and the European Extremely Large Telescope (E-ELT).

ALMA
Atacama Large Millimeter Array
The Atacama Large Millimeter/sub-millimeter Array is an array of radio telescopes in the Atacama desert of northern Chile. Since a high and dry site is crucial to millimeter wavelength operations, the array is being constructed on the Chajnantor plateau at 5000 metres altitude...

 is a revolutionary facility for the observation of the Universe
Universe
The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...

 in the millimeter/submillimetre
Terahertz radiation
In physics, terahertz radiation refers to electromagnetic waves propagating at frequencies in the terahertz range. It is synonymously termed submillimeter radiation, terahertz waves, terahertz light, T-rays, T-waves, T-light, T-lux, THz...

 range of radiation and is the largest ground-based astronomy project in existence. Its construction is well under way, being scheduled to be completed in 2013. The ALMA project is an international collaboration between Europe (represented by ESO), East Asia, North America and the Republic of Chile.

The E-ELT is a 40-metre class telescope that is currently in detailed design phase phase and will be the world's largest optical
Optical telescope
An optical telescope is a telescope which is used to gather and focus light mainly from the visible part of the electromagnetic spectrum for directly viewing a magnified image for making a photograph, or collecting data through electronic image sensors....

/near-infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

 telescope. The light-gathering power of this telescope will allow detailed studies of planets around other stars, the first objects in the Universe
Universe
The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...

, super-massive black holes
Supermassive black hole
A supermassive black hole is the largest type of black hole in a galaxy, in the order of hundreds of thousands to billions of solar masses. Most, and possibly all galaxies, including the Milky Way, are believed to contain supermassive black holes at their centers.Supermassive black holes have...

, and the nature and distribution of the dark matter
Dark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...

 and dark energy
Dark energy
In physical cosmology, astronomy and celestial mechanics, dark energy is a hypothetical form of energy that permeates all of space and tends to accelerate the expansion of the universe. Dark energy is the most accepted theory to explain recent observations that the universe appears to be expanding...

 which dominate the Universe. ESO has been working together with its user community of European astronomers and astrophysicists to define this new giant telescope since the end of 2005.

ESO's observing facilities have made important astronomical discoveries and produced several astronomical catalogues. Recent findings include the discovery of the farthest gamma-ray burst and the evidence for a black hole
Black hole
A black hole is a region of spacetime from which nothing, not even light, can escape. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole there is a mathematically defined surface called an event horizon that...

 at the centre of our galaxy, the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...

. In 2004, the VLT allowed astronomers to obtain the first picture of an extrasolar planet
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...

, 2M1207b
2M1207b
2M1207b is a planetary-mass object orbiting the brown dwarf 2M1207, in the constellation Centaurus, approximately 170 light-years from Earth...

, orbiting a brown dwarf
Brown dwarf
Brown dwarfs are sub-stellar objects which are too low in mass to sustain hydrogen-1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no chemical differentiation by depth...

 173 light-years away. The High Accuracy Radial Velocity Planet Searcher (HARPS) instrument, installed in another ESO telescope, led to the discovery of many other extrasolar planet
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...

s, including Gliese 581c, one of the smallest planets outside the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...

 found to date.

History

ESO Directors General
Otto Heckmann
Otto Heckmann
Otto Hermann Leopold Heckmann was a German astronomer.He directed the Hamburg Observatory from 1941 to 1962, after which he became the first director of the European Southern Observatory. , Otto Heckmann He actively contributed to the creation of the third issue of the Astronomische Gesellschaft...

1962–1969
Adriaan Blaauw 1970–1974
Lodewijk Woltjer
Lodewijk Woltjer
Lodewijk Woltjer studied at the University of Leiden under Jan Oort earning a PhD in astronomy in 1957 with a thesis on the Crab Nebula. This was followed by post-doctoral research appointments to various American universities and the subsequent appointment of professor of theoretical astrophysics...

1975–1987
Harry van der Laan 1988–1992
Riccardo Giacconi
Riccardo Giacconi
Riccardo Giacconi is an Italian/American Nobel Prize-winning astrophysicist who laid the foundations of X-ray astronomy. He is currently a professor at the Johns Hopkins University.- Biography :...

 (Nobel Prize
Nobel Prize
The Nobel Prizes are annual international awards bestowed by Scandinavian committees in recognition of cultural and scientific advances. The will of the Swedish chemist Alfred Nobel, the inventor of dynamite, established the prizes in 1895...

 winner)
1993–1999
Catherine Cesarsky
Catherine Cesarsky
Catherine Jeanne Cesarsky is a French astronomer currently residing in Germany, known for her successful research activities in several central areas of modern astrophysics. She was formerly president of the International Astronomical Union...

1999–2007
Tim de Zeeuw
Tim de Zeeuw
Pieter Timotheus "Tim" de Zeeuw is a Dutch astronomer specializing in the formation, structure and dynamics of galaxies. He was educated at...

from 2007


The idea that European astronomers should establish a common large observatory arose at the Leiden Observatory
Leiden Observatory
Leiden Observatory is an astronomical observatory in the city of Leiden, Netherlands. It was established by Leiden University in 1633, to house the quadrant of Snellius, and is the oldest operating University observatory in the world Leiden Observatory (Sterrewacht Leiden in Dutch) is an...

 in the Netherlands in the spring of 1953 between Walter Baade
Walter Baade
Wilhelm Heinrich Walter Baade was a German astronomer who worked in the USA from 1931 to 1959.-Biography:He took advantage of wartime blackout conditions during World War II, which reduced light pollution at Mount Wilson Observatory, to resolve stars in the center of the Andromeda galaxy for the...

 and Jan Oort
Jan Oort
Jan Hendrik Oort was a Dutch astronomer. He was a pioneer in the field of radio astronomy. The Oort cloud of comets bears his name....

. It was quickly followed up by Oort who, on the 21st of June of the same year, gathered a group of astronomers in Leiden to consider it. Immediately thereafter, the subject was further discussed at the Groningen conference, also in the Netherlands. On the 26th of January 1954, an ESO declaration was signed by leading astronomers from six European countries expressing the wish that a joint European observatory be established in the southern hemisphere.

The choice of the southern hemisphere resulted from the need to observe the southern sky. At the time, all large reflector telescopes (with an aperture
Aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are,...

 of 2 metres or more) were located in the northern hemisphere. In addition, some of the most interesting objects of research, such as the central parts of the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...

 and the Magellanic Clouds
Magellanic Clouds
The two Magellanic Clouds are irregular dwarf galaxies visible in the southern hemisphere, which are members of our Local Group and are orbiting our Milky Way galaxy...

, were accessible only from the southern hemisphere. The telescopes were to be set up in South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

, where several European observatories were located, but it was discovered (after testing observing conditions over the years of 1955 to 1963) that the Andes
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...

 were preferable. On the 15th of November 1963, Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

 was chosen as the site for ESO's observatory.

This decision was preceded by the ESO Convention, which was signed on the 5th of October 1962 by Belgium, Germany, France, the Netherlands and Sweden, and by the nomination (on the 1st of November 1962) of Otto Heckmann
Otto Heckmann
Otto Hermann Leopold Heckmann was a German astronomer.He directed the Hamburg Observatory from 1941 to 1962, after which he became the first director of the European Southern Observatory. , Otto Heckmann He actively contributed to the creation of the third issue of the Astronomische Gesellschaft...

 as the first Director General of the organisation. A first proposal for the Convention, between astronomy organisations in these five countries, was drafted in 1954. Although some amendments were made in the initial document, the matter of the Convention proceeded slowly until 1960, when it came into focus in that year's Committee meeting. The new draft was discussed in detail and one of the members, Bannier (who was also a member of the Council of CERN
CERN
The European Organization for Nuclear Research , known as CERN , is an international organization whose purpose is to operate the world's largest particle physics laboratory, which is situated in the northwest suburbs of Geneva on the Franco–Swiss border...

, the European Organisation for Nuclear Research), highlighted the need to have a Convention between governments and not only between organisations.

The matter of the Convention, and the involvement of governments in it, became pressing because the costs of site testing expeditions were rising sharply. The final 1962 text was largely adopted from the CERN Convention because of the similarities between the two organisations and because some of the members of the ESO Council were also members of the Council of CERN.

In 1966, the first of ESO's telescopes at the La Silla site in Chile began operating. Because CERN, like ESO, developed powerful and sophisticated instrumentation, the astronomy organisation frequently turned to the nuclear research body for informal consultation. Eventually, a collaborative agreement between ESO and CERN was signed in 1970. A few months after, ESO's Telescope Division had established itself in a CERN building in Geneva
Geneva
Geneva In the national languages of Switzerland the city is known as Genf , Ginevra and Genevra is the second-most-populous city in Switzerland and is the most populous city of Romandie, the French-speaking part of Switzerland...

. ESO's Sky Atlas Laboratory was also established on CERN premises. ESO's European departments moved into the new ESO Headquarters in Garching
Garching bei München
Garching bei München or Garching is a city in Bavaria, Germany near Munich. It is the home of several research institutes and university departments. It became a city on 14 September 1990.-Location:...

 near Munich
Munich
Munich The city's motto is "" . Before 2006, it was "Weltstadt mit Herz" . Its native name, , is derived from the Old High German Munichen, meaning "by the monks' place". The city's name derives from the monks of the Benedictine order who founded the city; hence the monk depicted on the city's coat...

, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 in 1980.

Member states

Member country Joined
1962
1962
1962
1962
1962
1967
1981
1982, 24 May
2000, 27 June
2002, 8 July
2004, 1 July
2006, 1 July
2007, 1 January
2008, 1 July
2010, 29 December (Formal ratification pending)

ESO's Observing Sites in Chile


While ESO's headquarters are located in Germany, all of its telescopes and observatories are in the north of Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

, where the organisation operates some of the world's largest and most advanced ground-based
Observatory
An observatory is a location used for observing terrestrial or celestial events. Astronomy, climatology/meteorology, geology, oceanography and volcanology are examples of disciplines for which observatories have been constructed...

 astronomical facilities:
  • La Silla
    La Silla Observatory
    La Silla Observatory is an astronomical observatory in Chile with three telescopes built and operated by the European Southern Observatory organisation, and several others are partly maintained by ESO...

    , which hosts the New Technology Telescope
    New Technology Telescope
    The New Technology Telescope or NTT is an Alt-Az, 3.58-metre Richey-Chretien telescope part of the European Southern Observatory and began operations in 1989. It is located in Chile at the La Silla Observatory and was an early pioneer on the use of active optics...

    ,
  • Paranal
    Paranal Observatory
    Paranal Observatory is an astronomical observatory located on Cerro Paranal at 2,635 m altitude and operated by the European Southern Observatory. The Very Large Telescope is the largest telescope on Paranal, actually composed of four separate 8.2 m telescopes...

    , where the Very Large Telescope
    Very Large Telescope
    The Very Large Telescope is a telescope operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. The VLT consists of four individual telescopes, each with a primary mirror 8.2m across, which are generally used separately but can be used together to...

     is located,
  • Llano de Chajnantor
    Llano de Chajnantor Observatory
    Llano de Chajnantor Observatory is an astronomical observatory located at an altitude of 5,104 m in the Chilean Atacama desert, 50 kilometers to the east of San Pedro de Atacama. It is a very dry site - inhospitable to humans - but an excellent site for submillimetre astronomy...

    , which hosts the APEX (Atacama Pathfinder Experiment
    Atacama Pathfinder Experiment
    The Atacama Pathfinder Experiment is a radio telescope located at 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert, in northern Chile, 50 kilometers to the east of San Pedro de Atacama. The main dish has a diameter of 12 meters and consists of 264...

    ) submillimetre telescope
    Submillimetre astronomy
    Submillimetre astronomy or submillimeter astronomy is the branch of observational astronomy that is conducted at submillimetre wavelengths of the electromagnetic spectrum. Astronomers place the submillimetre waveband between the far-infrared and microwave wavebands, typically taken to be between a...

     and where ALMA, the Atacama Large Millimeter/submillimeter Array, is currently under construction.


These are among the best locations for astronomical observations in the southern hemisphere.

One of the most ambitious ESO projects is the European Extremely Large Telescope (E-ELT), a 40-metre-class telescope based on an innovative 5-mirror design, following the concept of the formerly planned Overwhelmingly Large Telescope
Overwhelmingly Large Telescope
The Overwhelmingly Large Telescope is a conceptual design by the European Southern Observatory organization for an extremely large telescope, which was intended to have a single aperture of 100 meters in diameter...

. The E-ELT will be the largest optical/near-infrared telescope
Telescope
A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...

 in the world. ESO started the design phase of this telescope in early 2006 and aims to begin constructing it in 2012. As decided by the ESO Council on the 26th of April 2010, a fourth site, Cerro Armazones
Cerro Armazones
Cerro Armazones is a mountain located in the Sierra Vicuña Mackenna of the Chilean Coast Range, approximately 130 km south-east of Antofagasta in the Antofagasta Region, Chile. It has a height of 3,064 m and is located in a privileged zone for optical astronomy since it receives almost 350...

, is to be the home of E-ELT.

Each year, about 2000 proposals are made for the use of ESO telescopes, requesting between four and six times more nights than are available. The science done with these instruments annually results in a significant number of peer-reviewed publications. In 2009 alone, more than 650 refereed papers based on ESO data were published.
ESO Telescopes
Name Size Type Location
Very Large Telescope
Very Large Telescope
The Very Large Telescope is a telescope operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. The VLT consists of four individual telescopes, each with a primary mirror 8.2m across, which are generally used separately but can be used together to...

 (VLT)
4 x 8.2 m + 4 x 1.8 m optical, near- and mid-infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

 telescope array
Astronomical interferometer
An astronomical interferometer is an array of telescopes or mirror segments acting together to probe structures with higher resolution by means of interferometry....

 
Paranal
New Technology Telescope
New Technology Telescope
The New Technology Telescope or NTT is an Alt-Az, 3.58-metre Richey-Chretien telescope part of the European Southern Observatory and began operations in 1989. It is located in Chile at the La Silla Observatory and was an early pioneer on the use of active optics...

 (NTT)
3.58 m optical and infrared telescope La Silla
ESO 3.6 m telescope  3.57 m optical and infrared telescope La Silla
MPG/ESO 2.2 m telescope
MPG/ESO telescope
The MPG/ESO telescope is a 2.2-m ground-based telescope at the European Southern Observatory in La Silla, Chile. It was built by Zeiss and has been operating since 1984. It is on indefinite loan to the European Southern Observatory from the Max Planck Institute for Astronomy...

 
2.20 m optical and infrared telescope La Silla
Atacama Pathfinder Experiment
Atacama Pathfinder Experiment
The Atacama Pathfinder Experiment is a radio telescope located at 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert, in northern Chile, 50 kilometers to the east of San Pedro de Atacama. The main dish has a diameter of 12 meters and consists of 264...

 (APEX)
12 m millimetre-/submillimetre-wavelength telescope Chajnantor
Atacama Large Millimeter/submillimeter Array (ALMA) 50 x 12 m, and 12 x 7 m + 4 x 12 m (ACA) millimetre-/submillimetre-wavelength interferometer array telescope Chajnantor
Visible and Infrared Survey Telescope for Astronomy
VISTA (telescope)
The VISTA is a reflecting telescope with a 4.1 metre mirror, located at the Paranal Observatory in Chile. It is operated by the European Southern Observatory and saw first light in December 2009...

 (VISTA)
4.1 m near-infrared survey telescope Paranal
VLT Survey Telescope
VLT Survey Telescope
The VLT Survey Telescope is the latest telescope to be added to ESO’s Paranal Observatory in the Atacama Desert of northern Chile. It is housed in an enclosure immediately adjacent to the four Very Large Telescope Unit Telescopes on the summit of Cerro Paranal. The VST is a wide-field survey...

 (VST)
2.6 m optical survey telescope Paranal
European Extremely Large Telescope (E-ELT) 39.3 m optical to mid-infrared telescope Cerro Armazones
Cerro Armazones
Cerro Armazones is a mountain located in the Sierra Vicuña Mackenna of the Chilean Coast Range, approximately 130 km south-east of Antofagasta in the Antofagasta Region, Chile. It has a height of 3,064 m and is located in a privileged zone for optical astronomy since it receives almost 350...

 (in detailed design phase)


ESO's telescopes generate vast amounts of data at a high rate, which are stored in a permanent Science Archive Facility at ESO's headquarters. The archive now contains more than 1.5 million images or spectra with a total volume of about 65 terabytes (65,000,000,000,000 bytes) of data.

Additional ESO research facilities are located in Santiago, Chile. The space includes a library, computing resources, and programmes for visiting scientists.ESO also maintains close ties with other observatories and universities throughout the country.

La Silla


La Silla, located in the southern part of the Atacama desert, 600 km north of Santiago de Chile and at an altitude of 2400 metres, is the home of ESO's original observing site. Like other observatories in this geographical area, La Silla is located far from sources of light pollution and it has one of the darkest night skies on the Earth. In La Silla, ESO currently operates three major telescopes: the 3.6-metre Telescope, the New Technology Telescope (NTT), and the 2.2-metre Max-Planck-ESO Telescope.

Moreover, the observatory regularly hosts visitor instruments that are attached to a telescope for the duration of a run of observation and are removed thereafter. La Silla also hosts national telescopes, such as the 1.2-metre Swiss Telescope and the 1.5-metre Danish Telescope.

About 300 refereed publications per year are attributable to the work of the observatory; moreover, scientific discoveries done with La Silla telescopes include several 'firsts'. The HARPS spectrograph detected the system around Gliese 581, which contains what may be the first known rocky planet in a habitable zone, outside the Solar System. Several telescopes at La Silla played a crucial role in linking gamma-ray bursts—the most energetic explosions in the Universe since the Big Bang
Big Bang
The Big Bang theory is the prevailing cosmological model that explains the early development of the Universe. According to the Big Bang theory, the Universe was once in an extremely hot and dense state which expanded rapidly. This rapid expansion caused the young Universe to cool and resulted in...

 —with the explosions of massive stars. Since 1987, the ESO La Silla Observatory has also played an important role in the study and follow-up of the nearest recent supernova, SN 1987A
SN 1987A
SN 1987A was a supernova in the outskirts of the Tarantula Nebula in the Large Magellanic Cloud, a nearby dwarf galaxy. It occurred approximately 51.4 kiloparsecs from Earth, approximately 168,000 light-years, close enough that it was visible to the naked eye. It could be seen from the Southern...

.

ESO 3.6-metre Telescope


This telescope started operations in 1977 and set Europe the challenge of constructing and operating a 3–4-metre class telescope in the southern hemisphere. Over the years, it has been constantly upgraded, including the installation of a new secondary mirror
Secondary mirror
A secondary mirror is the second deflecting or focusing mirror element in a reflecting telescope. Light gathered by the primary mirror is directed towards a focal point typically past the location of the secondary. Secondary mirrors in the form of an optically flat diagonal mirror are used to...

 that has kept the telescope in its place as one of the most efficient and productive engines of astronomical research.

This conventionally designed horseshoe mount telescope, was mostly used for infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

 spectroscopy
Spectroscopy
Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...

. It now hosts the HARPS spectrograph, which is used for the search of extra-solar planets and for asteroseismology
Asteroseismology
Asteroseismology also known as stellar seismology is the science that studies the internal structure of pulsating stars by the interpretation of their frequency spectra. Different oscillation modes penetrate to different depths inside the star...

. The instrument is built to obtain very high long term radial velocity
Radial velocity
Radial velocity is the velocity of an object in the direction of the line of sight . In astronomy, radial velocity most commonly refers to the spectroscopic radial velocity...

 accuracy (on the order of 1 m/s).

New Technology Telescope (NTT)


The New Technology Telescope (NTT) is an alt-azimuth
Altazimuth mount
An altazimuth or alt-azimuth mount is a simple two-axis mount for supporting and rotating an instrument about two mutually perpendicular axes; one vertical and the other horizontal. Rotation about the vertical axis varies the azimuth of the pointing direction of the instrument...

, 3.58-metre, Ritchey-Chrétien
Ritchey-Chrétien telescope
A Ritchey–Chrétien telescope is a specialized Cassegrain telescope designed to eliminate coma, thus providing a large field of view compared to a more conventional configuration. An RCT has a hyperbolic primary and a hyperbolic secondary mirror. It was invented in the early 1910s by American...

 telescope inaugurated in 1989, the first in the world to have a computer-controlled main mirror. This mirror is flexible and its shape is actively adjusted during observations to preserve the optimal image quality. The secondary mirror position is also actively controlled in three directions. This technology, developed by ESO and known as active optics
Active optics
Active optics is a technology used with reflecting telescopes developed in the 1980s, which actively shapes a telescope's mirrors to prevent deformation due to external influences such as wind, temperature, mechanical stress...

, is now applied to all major modern telescopes, such as the VLT and the future E-ELT.
The design of the octagonal enclosure housing the NTT is another technological breakthrough. The telescope dome is relatively small, and is ventilated by a system of flaps that makes air flow smoothly across the mirror, reducing turbulence and leading to sharper images.

MPG/ESO 2.2-metre Telescope



The 2.2-metre Telescope has been in operation at La Silla since early 1984 and is on indefinite loan to ESO from the Max Planck Society (Max-Planck-Gesellschaft or MPG in German). Telescope time is shared between MPG and ESO observing programmes, while the operation and maintenance of the telescope are ESO’s responsibility.

Its instrumentation includes the 67-million pixel Wide Field Imager (WFI) with a field of view as large as the full Moon, which has taken many amazing images of celestial objects. Other instruments used are GROND, the Gamma-Ray Burst Optical/Near-Infrared Detector, which chases the afterglows of the most powerful explosions in the Universe, known as gamma-ray bursts, and the high-resolution spectrograph FEROS (the Fiber-fed Extended Range Optical Spectrograph), used to make detailed studies of stars.

Other telescopes


La Silla also hosts several national and project telescopes that are not operated by ESO. Among them, are: the Swiss 1.2-metre Euler Telescope, the Danish 1.54-metre Telescope, as well as the REM and the TAROT telescopes.

The Euler Telescope is a 1.2-metre telescope built and operated by the Observatory of Geneva
Observatory of Geneva
Observatoire de Genève is an astronomical observatory at Sauverny in the municipality of Versoix, Canton of Geneva, Switzerland...

 (Switzerland). It is used to conduct high-precision radial velocity measurements that mainly serve to search for large extrasolar planets in the southern celestial hemisphere. Its first success was the discovery of a planet in orbit around Gliese 86. Other observing programmes focus on variables stars
Variable star
A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth...

, asteroseismology, follow-up of gamma-ray bursters (GRB), monitoring of active galactic nuclei
Active galactic nucleus
An active galactic nucleus is a compact region at the centre of a galaxy that has a much higher than normal luminosity over at least some portion, and possibly all, of the electromagnetic spectrum. Such excess emission has been observed in the radio, infrared, optical, ultra-violet, X-ray and...

 (AGN) and gravitational lenses
Gravitational lens
A gravitational lens refers to a distribution of matter between a distant source and an observer, that is capable of bending the light from the source, as it travels towards the observer...

.
The 1.54-metre Danish telescope was built by Grubb-Parsons, and has been in use at La Silla since 1979. The telescope has an off-axis
Off-axis optical system
An off-axis optical system is an optical system in which the optical axis of the aperture is not coincident with the mechanical center of the aperture. An optical system in which the optical axis of the aperture is not coincident with the mechanical center of the aperture...

 mount and the optics are of a Ritchey-Chrétien design. On account of the telescope's mount and the limited space inside the dome, the telescope has significant pointing restrictions.

The Rapid Eye Mount Telescope (REM) is a small rapid-reaction automatic telescope with a primary mirror of 60 centimetre, in an alt-azimuth mount that started operations in October 2002. The main purpose of telescope is to follow the prompt afterglow of the GRBs detected by the NASA Swift
Swift Gamma-Ray Burst Mission
The Swift Gamma-Ray Burst Mission consists of a robotic spacecraft called Swift, which was launched into orbit on 20 November 2004, 17:16:00 UTC on a Delta II 7320-10C expendable launch vehicle. Swift is managed by the NASA Goddard Space Flight Center, and was developed by an international...

 satellite.

The TAROT (Télescope à Action Rapide pour les Objets Transitoires, Rapid Action Telescope for Transient Objects) is a very fast moving (1 second) optical robotic telescope able to observe from the beginning of a gamma-ray burst (GRB). Satellites detecting GRBs send timely signals to TAROT, which in turn is able to give a sub-arc second position to the astronomical community. The data from the TAROT telescope are also useful to study the evolution of GRBs, the physics of the fireball and of the surrounding material.

Paranal



The Paranal Observatory is located on top of Cerro Paranal, in the Atacama Desert, in the northern part of Chile. Cerro Paranal is a 2,635-metre high mountain, located about 120 km south of the town of Antofagasta
Antofagasta
Antofagasta is a port city in northern Chile, about north of Santiago. It is the capital of Antofagasta Province and Antofagasta Region. According to the 2002 census, the city has a population of 296,905...

 and 12 km inland from the Pacific coast.

Paranal Observatory has three major telescopes operating in the visible and infrared light: the Very Large Telescope (VLT, four 8.2-metre Unit Telescopes, plus four 1.8-metre Auxiliary Telescopes), the VLT Survey Telescope (VST, 2.6 metres in diameter), and the Visible and Infrared Survey Telescope for Astronomy (VISTA, 4.1 metres in diameter).

Additionally, in March 2008, Paranal was the location for the filming of several scenes in the 22nd James Bond movie, Quantum of Solace.

Very Large Telescope


The main facility at Paranal is the VLT. It is an optical/near and mid-infrared telescope consisting of four near-identical 8.2-metre Unit Telescopes (UTs), each hosting two or three instruments. These large telescopes can also work together, in groups of two or three, to form a giant 'interferometer', the ESO Very Large Telescope Interferometer or VLTI, allowing astronomers to see details up to 25 times finer than those seen with the individual telescopes. The light beams are combined in the VLTI using a complex system of mirrors located in underground tunnels where the light paths must be kept equal to distances less than 1/1000 mm over a hundred metres. With this kind of precision, the VLTI can achieve an angular resolution
Angular resolution
Angular resolution, or spatial resolution, describes the ability of any image-forming device such as an optical or radio telescope, a microscope, a camera, or an eye, to distinguish small details of an object...

 of milliarcseconds
Minute of arc
A minute of arc, arcminute, or minute of angle , is a unit of angular measurement equal to one sixtieth of one degree. In turn, a second of arc or arcsecond is one sixtieth of one minute of arc....

, equivalent to distinguishing the two headlights of a car at the distance of the Moon.

The first of the UTs had its first light in May 1998 and was offered to the astronomical community on the 1st of April 1999. The other telescopes followed suit in 1999 and 2000, thus making the VLT fully operational. Four 1.8-metre Auxiliary Telescopes (ATs) have been added to the VLTI to make it available when the UTs are being used for other projects. These ATs were installed between 2004 and 2007.
Results from the VLT have led to the publication of an average of more than one peer-reviewed scientific paper per day. For instance, only in 2007, almost 500 refereed scientific papers were published based on VLT data. The VLT's scientific discoveries include imaging an extrasolar planet for the first time, tracking individual stars moving around the supermassive black hole
Supermassive black hole
A supermassive black hole is the largest type of black hole in a galaxy, in the order of hundreds of thousands to billions of solar masses. Most, and possibly all galaxies, including the Milky Way, are believed to contain supermassive black holes at their centers.Supermassive black holes have...

 at the centre of the Milky Way, and observing the afterglow of the furthest known gamma-ray burst.
Mapuche names for the Unit Telescopes

It had long been ESO's intention to provide "real" names to the four VLT Unit Telescopes, to replace the original, somewhat dry and technical designations of UT1 to UT4. In March 1999, at the time of the Paranal inauguration, four meaningful names of objects in the sky in the Mapuche
Mapuche
The Mapuche are a group of indigenous inhabitants of south-central Chile and southwestern Argentina. They constitute a wide-ranging ethnicity composed of various groups who shared a common social, religious and economic structure, as well as a common linguistic heritage. Their influence extended...

 language were chosen. This indigenous people lives mostly south of Santiago de Chile.

An essay contest was arranged in this connection among schoolchildren of the Chilean II Region of which Antofagasta is the capital to write about the implications of these names. It drew many entries dealing with the cultural heritage of ESO's host country.

The winning essay was submitted by 17-year old Jorssy Albanez Castilla from Chuquicamata
Chuquicamata
Chuquicamata, or "Chuqui" as it is more familiarly known, is by digged volume the biggest open pit copper mine in the world, located in the north of Chile, 215 km northeast of Antofagasta and 1,240 km north of the capital, Santiago...

, near the city of Calama
Calama, Chile
Calama is a city and commune in the Atacama Desert in northern Chile. It is the capital of El Loa Province, part of the Antofagasta Region. Calama is one of the driest cities in the world with average annual precipitation of just . The River Loa, Chile's longest, flows through the city...

. She received the prize, an amateur telescope, during the Paranal Inauguration.

The four Unit Telescopes are now known as:
  • Antu (UT1; The Sun)
  • Kueyen (UT2; The Moon)
  • Melipal (UT3; The Southern Cross)
  • Yepun (UT4; Venus
    Venus
    Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...

    —as evening star)


Originally translated as "Sirius
Sirius
Sirius is the brightest star in the night sky. With a visual apparent magnitude of −1.46, it is almost twice as bright as Canopus, the next brightest star. The name "Sirius" is derived from the Ancient Greek: Seirios . The star has the Bayer designation Alpha Canis Majoris...

", it now seems that "Yepun" actually means "Venus".

Survey Telescopes


Visible and Infrared Survey Telescope for Astronomy (VISTA) is housed on the peak adjacent to the one hosting the VLT and shares the same exceptional observing conditions. VISTA’s main mirror is 4.1 metres across and is the most highly curved mirror of this size and quality ever made—its deviations from a perfect surface are less than a few thousandths of the thickness of a human hair—and its construction and polishing presented formidable challenges.

VISTA was conceived and developed by a consortium of 18 universities in the United Kingdom led by Queen Mary, University of London
Queen Mary, University of London
Queen Mary, University of London is a public research university located in London, United Kingdom and a constituent college of the federal University of London...

 and became an in-kind contribution to ESO as part of the UK's accession agreement. The telescope design and construction were project-managed by the Science and Technology Facilities Council's UK Astronomy Technology Centre
UK Astronomy Technology Centre
The UK Astronomy Technology Centre is based at the Royal Observatory in Edinburgh, Scotland, and is part of the Science and Technology Facilities Council....

 (STFC, UK ATC). Provisional acceptance of VISTA was formally granted by ESO at a ceremony at ESO's Headquarters in Garching, Germany, attended by representatives of Queen Mary, University of London and STFC, on 10 December 2009. Since then, the telescope has been operated by ESO., also capturing stunning images since it started operating.

The VLT Survey Telescope
VLT Survey Telescope
The VLT Survey Telescope is the latest telescope to be added to ESO’s Paranal Observatory in the Atacama Desert of northern Chile. It is housed in an enclosure immediately adjacent to the four Very Large Telescope Unit Telescopes on the summit of Cerro Paranal. The VST is a wide-field survey...

 (VST) is a state-of-the-art 2.6-metre telescope equipped with OmegaCAM, a 268 megapixel CCD camera with a field of view four times the area of the full Moon. It complements VISTA as it will survey the sky in the visible light. The VST is the result of a joint venture between ESO and the Astronomical Observatory of Capodimonte
Astronomical Observatory of Capodimonte
The Osservatorio Astronomico di Capodimonte The Osservatorio Astronomico di Capodimonte The Osservatorio Astronomico di Capodimonte (Astronomical Observatory of Capodimonte is an astronomical observatory owned and operated by Italy's Istituto Nazionale di Astrofisica (National Institute for...

, Naples, a research centre of the Italian National Institute for Astrophysics INAF
INAF
The Istituto Nazionale di Astrofisica , or INAF for short, is the most important Italian institution conducting scientific research in astronomy and astrophysics. Researches performed by the scientific staff of the Institute go from the study of the planets and minor bodies of the solar system up...

. The VST became operational in 2011.

The scientific goals of both surveys range from the nature of dark energy to the threat of near-Earth asteroids. Large teams of astronomers throughout Europe will conduct the surveys. Some of them will cover most of the southern sky while others will focus on smaller areas.

Both VISTA and the VST are expected to produce huge quantities of data given that a single picture taken by VISTA has 67 megapixels and images from OmegaCam on the VST will have 268 megapixels. The two Survey Telescopes will produce far more data every night than all the other instruments on the VLT together. The VST and VISTA will produce more than 100 Terabytes of data per year.

Llano de Chajnantor


The Llano de Chajnantor is a 5,100-metre high plateau in the Chilean Atacama Desert
Atacama Desert
The Atacama Desert is a plateau in South America, covering a strip of land on the Pacific coast, west of the Andes mountains. It is, according to NASA, National Geographic and many other publications, the driest desert in the world...

, about 50 kilometres east of
San Pedro de Atacama
San Pedro de Atacama
San Pedro de Atacama is a Chilean town and commune in El Loa Province, Antofagasta Region. It is located east of Antofagasta, some 106 km southeast of Calama and the Chuquicamata copper mine, overlooking the Licancabur volcano. It features a significant archeological museum, the R. P...

. The site is 750 metres higher than the observatories on Mauna Kea
Mauna Kea Observatory
The Observatories at Mauna Kea, , are an independent collection of astronomical research facilities located on the summit of Mauna Kea on the Big Island of Hawai'i, USA. The facilities are located in a special land use zone known as the "Astronomy Precinct," which is located in the Mauna Kea...

 and 2400 metres higher than the VLT in Cerro Paranal.

It is a very dry place—inhospitable to humans—but an excellent site for submillimetre astronomy
Submillimetre astronomy
Submillimetre astronomy or submillimeter astronomy is the branch of observational astronomy that is conducted at submillimetre wavelengths of the electromagnetic spectrum. Astronomers place the submillimetre waveband between the far-infrared and microwave wavebands, typically taken to be between a...

.
Water vapor
Water vapor
Water vapor or water vapour , also aqueous vapor, is the gas phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Under typical atmospheric conditions, water vapor is continuously...

 molecules in Earth's atmosphere
Earth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...

 absorb and attenuate submillimetre radiation and thus a dry site is required for this type of radio astronomy
Radio astronomy
Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The initial detection of radio waves from an astronomical object was made in the 1930s, when Karl Jansky observed radiation coming from the Milky Way. Subsequent observations have identified a number of...

.

The telescopes that can be found here are:
  • Atacama Cosmology Telescope
    Atacama Cosmology Telescope
    The Atacama Cosmology Telescope is a six-metre telescope on Cerro Toco in the Atacama Desert in the north of Chile, near the Llano de Chajnantor Observatory. It is designed to make high-resolution, microwave-wavelength surveys of the sky in order to study the cosmic microwave background radiation...

     (ACT, not operated by ESO)
  • Atacama Pathfinder Experiment
    Atacama Pathfinder Experiment
    The Atacama Pathfinder Experiment is a radio telescope located at 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert, in northern Chile, 50 kilometers to the east of San Pedro de Atacama. The main dish has a diameter of 12 meters and consists of 264...

     (APEX)
  • Atacama Large Millimeter Array
    Atacama Large Millimeter Array
    The Atacama Large Millimeter/sub-millimeter Array is an array of radio telescopes in the Atacama desert of northern Chile. Since a high and dry site is crucial to millimeter wavelength operations, the array is being constructed on the Chajnantor plateau at 5000 metres altitude...

     (ALMA)
  • Q/U Imaging Experiment
    QUIET
    QUIET is an astronomy experiment to study the polarization of the cosmic microwave background radiation. QUIET stands for Q/U Imaging ExperimenT. The Q/U in the name refers to the ability of the telescope to measure the Q and U Stokes parameters simultaneously...

     (QUIET, not operated by ESO)


APEX and ALMA are telescopes designed for millimetre and submillimetre astronomy. This type of astronomy is a relatively unexplored frontier and reveals a Universe that cannot be seen in the more familiar visible or infrared light. It is ideal for studying the "cold Universe": light at these wavelengths shines from vast cold clouds in interstellar space, at temperatures only a few tens of degrees above absolute zero
Absolute zero
Absolute zero is the theoretical temperature at which entropy reaches its minimum value. The laws of thermodynamics state that absolute zero cannot be reached using only thermodynamic means....

. Astronomers use this light to study the chemical and physical conditions in these molecular clouds
Molecular cloud
A molecular cloud, sometimes called a stellar nursery if star formation is occurring within, is a type of interstellar cloud whose density and size permits the formation of molecules, most commonly molecular hydrogen ....

 —the dense regions of gas and cosmic dust where new stars are being born. Seen in visible light, these regions of the Universe are often dark and obscured due to the dust, but they shine brightly in the millimetre and submillimetre part of the electromagnetic spectrum
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....

. This wavelength range is also ideal for studying some of the earliest and most distant galaxies in the Universe, whose light has been redshifted
Redshift
In physics , redshift happens when light seen coming from an object is proportionally increased in wavelength, or shifted to the red end of the spectrum...

 into these longer wavelengths, as an effect of the expansion of the Universe.

Atacama Pathfinder Experiment (APEX)


The Atacama Pathfinder Experiment telescope is operated by ESO in collaboration with the Max Planck Institute for Radio Astronomy
Max Planck Institute for Radio Astronomy
The Max Planck Institute for Radio Astronomy is located in Bonn, Germany. It is one of 80 institutes in the Max Planck Society .-History:...

 (Bonn
Bonn
Bonn is the 19th largest city in Germany. Located in the Cologne/Bonn Region, about 25 kilometres south of Cologne on the river Rhine in the State of North Rhine-Westphalia, it was the capital of West Germany from 1949 to 1990 and the official seat of government of united Germany from 1990 to 1999....

, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

) and the Onsala Space Observatory
Onsala Space Observatory
Onsala Space Observatory , the Swedish National Facility for Radio Astronomy, provides scientists with equipment to study the Earth and the rest of the Universe. The observatory operates two radio telescopes in Onsala, 45 km south of Göteborg, and takes part in several international projects...

 (Onsala
Onsala
Onsala is a locality situated in Kungsbacka Municipality, Halland County, Sweden, with 11,375 inhabitants in 2005. It is also the biggest peninsula in Sweden, south of Gothenburg....

, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

). It is a 12-metre diameter telescope, the largest of its kind working in the southern hemisphere, operating at millimetre and submillimetre wavelengths—a range if radiations between infrared light and microwaves
Microwave
Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...

.
APEX also serves as a pathfinder for ALMA, the Atacama Large Millimeter Array
Atacama Large Millimeter Array
The Atacama Large Millimeter/sub-millimeter Array is an array of radio telescopes in the Atacama desert of northern Chile. Since a high and dry site is crucial to millimeter wavelength operations, the array is being constructed on the Chajnantor plateau at 5000 metres altitude...

, a revolutionary astronomical interferometer
Astronomical interferometer
An astronomical interferometer is an array of telescopes or mirror segments acting together to probe structures with higher resolution by means of interferometry....

 that ESO, together with its international partners, is now building on the Chajnantor plateau. APEX is based on a prototype ALMA antenna, modified to be operated as single dish radio telescope
Radio telescope
A radio telescope is a form of directional radio antenna used in radio astronomy. The same types of antennas are also used in tracking and collecting data from satellites and space probes...

.

Atacama Large Millimeter/submillimeter Array (ALMA)


ALMA is an astronomical interferometer
Astronomical interferometer
An astronomical interferometer is an array of telescopes or mirror segments acting together to probe structures with higher resolution by means of interferometry....

 of revolutionary design initially composed of 66 high-precision antennas, and operating at wavelengths of 0.3 to 3.6 mm. Its main array will have fifty 12-metre antennas, acting together as a single telescope—an interferometer. An additional compact array of four 12-metre and twelve 7-metre antennas will complement this. The antennas can be spread across the desert plateau over distances from 150 metres to 16 kilometres, which will give ALMA a powerful variable "zoom"—watch a video of an ALMA transporter to see how the antennas are moved. ALMA will be able to probe the Universe at millimeter and submillimeter wavelengths with unprecedented sensitivity and resolution, with a vision up to ten times sharper than the Hubble Space Telescope
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...

, and complementing images made with the VLT Interferometer. ALMA results from a collaboration between East Asia (Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

 and Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...

), Europe (ESO), North America (USA and Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

), and Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

.

Science goals of ALMA include studying the origins and formation of stars, galaxies, and planets, with observations of molecular gas and dust, distant galaxies towards the edge of the observable Universe, and the relic radiation
Cosmic microwave background radiation
In cosmology, cosmic microwave background radiation is thermal radiation filling the observable universe almost uniformly....

 of the Big Bang. The release of the call for ALMA science proposals happened on 31 March 2011 and the early science observations started on October 3d, 2011.

The search for planets outside our Solar System



"Is there life elsewhere in the Universe?" possibly is one of the Mankind's most profound —and still unanswered— questions. A key step of the human attempt to answer this question is the search for planets outside the Solar System. ESO's observatories are equipped with a unique arsenal of instruments for finding, studying and monitoring these so-called exoplanets. In 2004, the Very Large Telescope detected the faint glow of what seemed to be a planet orbiting a star located some 200 light-years away from the Earth. A year after, in 2005, this detection was confirmed to be the first picture of an exoplanet ever. Although this planet is a giant one, some five times more massive than Jupiter, this observation marks a first major step towards the characterization of the physical structure and chemical composition of exoplanets.

In spite of the fact that planets seem to be very common in the Universe, they are extremely tiny and faint objects at cosmic scales. This makes their direct detection very difficult, with the current technology. For this reason, most of the exoplanets discovered so far have been detected with indirect methods. Among these methods, the most successful has been the radial velocity method. HARPS, the High Accuracy Radial velocity Planet Searcher, has allowed the discovery of a significant number of planets with masses below that of Neptune, orbiting a nearby stars. Few of these planets are among the smallest ever discovered or reside in its star's habitable zone
Habitable zone
In astronomy and astrobiology, a habitable zone is an umbrella term for regions that are considered favourable to life. The concept is inferred from the empirical study of conditions favourable for Life on Earth...

. Particularly, it exists the possibility that one of these planets is covered by oceans—a waterworld. This discovery marks a groundbreaking result in the search for planets that could support life.

Finally, in the framework of three different global campaigns, the Danish 1,54-metre Telescope at La Silla participated in the discovery of one of the most Earth-like planets found so far. The planet, detected using the microlensing technique, is only about five times as massive as the Earth, circles its parent star in about 10 years, and most certainly has a rocky/icy surface.

The determination of the age of the Universe



By using the Very Large Telescope, astronomers have carried out an independent determination of the age of the Universe and have thrown new light on the earliest stages of our Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...

. They measured for the first time the amount of the radioactive isotope  uranium-238 in a star that was born when the Milky Way, the galaxy in which we live, was still forming.

Like carbon dating in archaeology, but over even longer timescales, this uranium 'clock' measures the age of the star. It shows that the star is 12.5 billion years old. Since the star cannot be older than the Universe itself, the Universe must be even older than this. This agrees with what we know from cosmology
Cosmology
Cosmology is the discipline that deals with the nature of the Universe as a whole. Cosmologists seek to understand the origin, evolution, structure, and ultimate fate of the Universe at large, as well as the natural laws that keep it in order...

, which gives an age of the Universe
Age of the universe
The age of the universe is the time elapsed since the Big Bang posited by the most widely accepted scientific model of cosmology. The best current estimate of the age of the universe is 13.75 ± 0.13 billion years within the Lambda-CDM concordance model...

 of 13.7 billion years. The star, and our galaxy, must have formed very soon after the Big Bang.

Another result is the first ever measurement of the beryllium
Beryllium
Beryllium is the chemical element with the symbol Be and atomic number 4. It is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl and chrysoberyl...

 content of two stars, in a globular cluster
Globular cluster
A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers. The name of this category of star cluster is...

 in the Milky Way. With this measurement, astronomers found that the first generation of stars in our galaxy must have formed soon after the end of the ~200 million-year long 'Dark Ages
Timeline of the Big Bang
This timeline of the Big Bang describes the history of the universe according to the prevailing scientific theory of how the universe came into being, using the cosmological time parameter of comoving coordinates...

' that followed the Big Bang.

A black hole at the centre of our galaxy


What lies at the center of the Milky Way? For a long time, astronomers have suspected that a black hole lurks at the heart of our galaxy, but could not be sure. A conclusive evidence was obtained after 16 years of regular monitoring of the Galactic Centre with ESO telescopes at La Silla and Paranal Observatories.

Stars at the centre of the Milky Way are so densely packed that special imaging techniques such as adaptive optics
Adaptive optics
Adaptive optics is a technology used to improve the performance of optical systems by reducing the effect of wavefront distortions. It is used in astronomical telescopes and laser communication systems to remove the effects of atmospheric distortion, and in retinal imaging systems to reduce the...

 were needed to boost the resolution of the VLT. Thanks to this, astronomers were able to watch individual stars with unprecedented accuracy as they moved around the galactic centre. Their paths conclusively showed that they must be orbiting in the immense gravitational grip of a supermassive black hole, almost three million times more massive than the Sun. The VLT observations also revealed flashes of infrared light emerging from the region at regular intervals. Whilst the exact cause of this phenomenon remains unknown, observers have suggested the black hole may be spinning rapidly. Whatever is happening, the black hole's life is not all peace and quiet.

The VLT has also been used to peer into the centres of galaxies beyond our own, where clear signs of activity produced by supermassive black holes are found. In the active galaxy NGC 1097, a complex network of filaments spiralling from the main part of the galaxy down to the centre was seen with extraordinary detail.

Gamma-ray bursts


Gamma-ray bursts (GRBs) are bursts of highly energetic gamma rays lasting from less than a second to several minutes—the blink of an eye on cosmological timescales. They are known to occur at huge distances from Earth, towards the limits of the observable Universe.

The VLT has observed the afterglow of a gamma-ray burst that is the farthest known. With a measured redshift of 8.2, the light from this very remote astronomical source has taken more than 13,000 million years to reach us. It is thus seen when the Universe was less than 600 million years old, or less than five per cent its present age. It must have released 300 times as much energy in a few seconds as the Sun will in its entire lifetime of more than 10,000 million years. GRBs are therefore the most powerful explosions in the Universe since the Big Bang.

The nature of these explosions has remained a mystery for a long time. Observations show that GRBs come in two types—short-duration (shorter than a few seconds), and long-duration—and it was suspected that two different kinds of cosmic event caused them. In 2003, ESO telescopes played a key role in following the aftermath of an explosion for a whole month. The observations showed that the light had similar properties to that from a supernova. This fact allowed astronomers linking long-duration GRBs with the ultimate explosions of massive stars, known as 'hypernovae
Hypernova
Hypernova , also known as a type 1c Supernova, refers to an incredibly large star that collapses at the end of its lifespan...

'. In 2005, ESO telescopes detected, for the first time, the visible light following a short-duration burst and tracked this light for three weeks. This time, the conclusion was that the short-duration bursts could not be caused by a hypernova. Instead, it is thought that they originate in the violent mergers of neutron stars or black holes.
Observations of gamma-ray burst afterglows were also coordinated between the VLT and the Atacama Pathfinder Experiment
Atacama Pathfinder Experiment
The Atacama Pathfinder Experiment is a radio telescope located at 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert, in northern Chile, 50 kilometers to the east of San Pedro de Atacama. The main dish has a diameter of 12 meters and consists of 264...

 (APEX) in order to identify the possible counterpart and its decay at submillimeter wavelengths.

Science archive and the digital universe



The Science Archive Operation Group receives and redistributes ESO and HST data and provides front-line archive user support. About 12 Terabytes (TB) of public data are distributed per year through the ESO archive, following about 10,000 web requests. Additionally, more than 2,000 CDs and DVDs of proprietary data are sent out annually to their respective Principal Investigators
Principal investigator
A principal investigator is the lead scientist or engineer for a particular well-defined science project, such as a laboratory study or clinical trial....

 for observations made in service mode. The current total archive holding is about 65 TB, with an input rate of about 15 TB per year. This is being drastically increased by a factor of 10 or so due to the Survey Telescopes' data production rate.

Major breakthroughs in telescope, detector, and computer technology now allow astronomical surveys to produce massive amounts of images, spectra, and catalogues. These datasets cover the sky at all wavelengths from gamma- and X-rays, through optical and infrared, to radio waves. Astronomers are developing ways to do new science, by making the huge amount of data in this 'digital Universe' easily accessible. These techniques use the so-called grid paradigm of distributed computing, with seamless and transparent access to the data through 'Virtual Observatories' (VOs).
Just as a physical observatory has telescopes, each with unique astronomical instruments, a VO consists of data centres, each with unique collections of astronomical data, soft-ware systems and processing capabilities. This global, community-based initiative is being developed world-wide under the auspices of the International Virtual Observatory Alliance and in Europe under the framework of the EURO-VO project.

VOs have already proved their effectiveness, for example by discovering 31 new optically faint, obscured quasar
Quasar
A quasi-stellar radio source is a very energetic and distant active galactic nucleus. Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than...

 candidates in the existing Great Observatories Origins Deep Survey
Great Observatories Origins Deep Survey
The Great Observatories Origins Deep Survey or GOODS is an astronomical survey combining deep observations from three of NASAs Great Observatories: the Hubble Space Telescope, the Spitzer Space Telescope and the Chandra X-ray Observatory along with data from other space-based telescopes, such as...

(GOODS) fields, quadrupling the number previously found. The discovery means that surveys of powerful supermassive black holes have so far underestimated their numbers by at least a factor of two, and possibly by up to a factor of five.

ESO's top 10 astronomical discoveries


1. Stars orbiting the Milky Way black hole

Several of ESO's flagship telescopes were used in a 16-year long study to obtain the most detailed view ever of the surroundings of the monster lurking at the heart of our galaxy,—a supermassive black hole.

2. Accelerating Universe

Two independent research teams have shown that the expansion of the Universe is accelerating—based on observations of exploding stars with astronomical telescopes at La Silla. The research teams where awarded the 2011 Nobel Prize in Physics
Nobel Prize in Physics
The Nobel Prize in Physics is awarded once a year by the Royal Swedish Academy of Sciences. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others are the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and...

 for said discovery.

3. First image of an exoplanet

The VLT has obtained the first-ever image of a planet outside our Solar System. The 5-Jupiter-mass planet orbits a failed star—a brown dwarf
Brown dwarf
Brown dwarfs are sub-stellar objects which are too low in mass to sustain hydrogen-1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no chemical differentiation by depth...

—at a distance of 55 times the mean Earth-Sun distance.

4. Gamma-ray bursts—the connections with supernovae and merging neutron stars

ESO telescopes have provided definitive proof that long gamma-ray bursts are linked with the ultimate explosion of massive stars; on the other hand, short gamma-ray bursts seem to be produced by merging neutron stars.

5. Cosmic temperature independently measured

The VLT has detected for the first time carbon monoxide molecules in a galaxy located almost 11,000 million light-years away. This has allowed astronomers to obtain the most precise measurement of the cosmic temperature at such a remote epoch.

6. Oldest star known in the Milky Way

Using ESO's VLT, astronomers have measured the age of the oldest star known in our galaxy, the Milky Way. At 13,200 million years old, the star was born in the earliest era of star formation in the Universe.

7. Flares from the supermassive black hole at the centre of the Milky Way

The VLT and APEX teamed up to study the violent flares from the supermassive black hole at the centre of the Milky Way, revealing material being stretched out as it orbits in the intense gravity close to the central black hole.

8. Direct measurements of the spectra of exoplanets and their atmospheres

The atmosphere around a super-Earth exoplanet has been analysed for the first time using the VLT. The planet, which is known as GJ 1214b, was studied as it passed in front of its parent star and some of the starlight passed through the planet’s atmosphere.

9. Richest planetary system

Astronomers using ESO’s HARPS have discovered a planetary system containing at least five planets, orbiting the Sun-like star HD 10180. Also evidence that two other planets may be present, one of which would have the lowest mass ever found.

10. Milky Way stellar motions

After more than 1000 nights of observations at La Silla, spread over 15 years, astronomers have determined the motions of more than 14,000 Sun-like stars residing in the neighbourhood of the Sun, showing that our home galaxy has led a much more turbulent and chaotic life than previously assumed.

Outreach activities



Outreach activities are carried out by the ESO education and Public Outreach Department (ePOD). These activities include a wide range of programs and products that aim to meet the specific requirements of media, science communicators and the general public, such as press releases, images, videos, as well as high-quality printed material.
Events such as the International Year of Astronomy 2009 (IYA2009) (with IAU
IAU
IAU may refer to:*International Astronomical Union*International American University*International American University College of Medicine*International Association of Universities*International Association of Ultrarunners...

 and UNESCO
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations...

), VLT First Light, Astronomy On-line, and the S-L 9 impact, have come out of the Department. ePOD also organises exhibitions and educational campaigns (Venus Transit
Transit of Venus
A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and Earth, becoming visible against the solar disk. During a transit, Venus can be seen from Earth as a small black disk moving across the face of the Sun...

, Science on Stage
Science on Stage Europe
The European initiave Science on Stage - initially launched as Physics on Stage in 1999 – is designed for European teachers to share good practice in science teaching and to discuss ways of improving the quality of science lessons. This is driven by the foreseen lack of young scientists in all...

 and Science in School are past examples).
A large collection of photos and videos can be found in the ESO's Public Image Gallery and ESO's Video Library]. A series of products from educational material to press kits can be downloaded for free from the ePOD website] or ordered in "physical form".
As part of the Department, European outreach for the NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

/ESA Hubble Space Telescope provides comprehensive information about this telescope and its scientific discoveries. The International Astronomical Union (IAU) Press Office is also hosted as part of ePOD.

Press releases and other products


ESO press releases describe important scientific, technical and organisation developments and achievements, as well as results obtained by scientists using ESO facilities.

ESO publishes three different types of press releases. Science releases describe scientific results usually appearing in a peer-reviewed journal that involve data from ESO observatories or ESO staff. Organisation releases cover a range of themes related to ESO operations, including news on current and future observatories, new astronomical instruments, and announcements of exhibitions all over the world. Finally, ESO selects its best astronomical images and presents them to the public in periodic photo releases.

All press releases, dating back to 1985, are available online. There are also child-friendly versions as well as press releases translated into the languages of ESO's member countries.

ESO also publishes Announcements and Pictures of the Week on its website. Announcements are shorter than press releases (typically below 200 words) and highlight stories and events which are of interest to the community. Pictures of the Week show beautiful or interesting photos from ESO telescopes, and can highlight recent events or archival photos. All former entries are available on the website.

ESOcast is a video podcast series dedicated to bringing the latest news and research from ESO—Astronomy made on planet Earth. Here the Universe's ultimate frontier is explored with Doctor J, also known as Dr. Joe Liske who is a German astronomer at ESO. His scientific interests are in cosmology, particularly on galaxy evolution and quasars.

Gallery


These images are among the best ones from ESO Top 100 Images.

See also

  • Atacama Large Millimeter Array
    Atacama Large Millimeter Array
    The Atacama Large Millimeter/sub-millimeter Array is an array of radio telescopes in the Atacama desert of northern Chile. Since a high and dry site is crucial to millimeter wavelength operations, the array is being constructed on the Chajnantor plateau at 5000 metres altitude...

  • European Extremely Large Telescope
  • Very Large Telescope
    VLT
    VLT may stand for:* Very Large Telescope, a system of four large optical telescopes organized in an array formation, located in northern Chile...


External links