European Southern Observatory

The European Southern Observatory (ESO) is an intergovernmental research organisation with 16 member states. It studies the night sky from the ground. ESO was created in 1962 and has over 750 staff members. Each year, it gets money from its member states.

ESO has built and runs some of the biggest and most advanced telescopes in the world. These include the 3.6 m New Technology Telescope, the Very Large Telescope (VLT), and the Atacama Large Millimeter Array. These telescopes help scientists see faraway stars, galaxies, and other objects in space very clearly.

One of ESO's newest projects is the Extremely Large Telescope, which is still being built. When it is finished, it will be the world's largest optical reflecting telescope. This huge telescope will help scientists study planets around other stars, the very first objects in the universe, and mysterious things like supermassive black holes, dark matter, and dark energy.

ESO's telescopes have helped make many important discoveries. For example, they found the most distant gamma-ray burst and evidence for a black hole at the centre of our Milky Way. In 2004, the VLT helped scientists take the first picture of an extrasolar planet orbiting a star 173 light-years away. Another instrument called the High Accuracy Radial Velocity Planet Searcher (HARPS) helped find many planets outside our Solar System.

Past

The European Southern Observatory (ESO) started as an idea in 1953. Astronomers Walter Baade and Jan Oort wanted to build a big shared observatory. In 1954, astronomers from six European countries agreed to support a joint observatory in the southern hemisphere.

Back then, all big telescopes were in the northern hemisphere. But some important parts of the sky, like the center of the Milky Way and the Magellanic Clouds, could only be seen from the south. First, South Africa was considered. But tests showed that a site in the Andes mountains of Chile was better. ESO signed its official agreement in 1962, and Chile was chosen as the location in 1963.

The first ESO telescope in Chile began working in 1966. Over time, ESO grew and moved its headquarters to Garching, Germany. In 2015, an ESO astronomer confirmed a planet orbiting the star Proxima Centauri.

Country	Accession
Belgium	1962
Germany	1962
France	1962
Netherlands	1964
Sweden	1964
Denmark	1967
Switzerland	1982
Italy	1982
Portugal	1 January 2001
United Kingdom	8 July 2002
Finland	1 July 2004
Spain	1 July 2006
Czech Republic	1 January 2007
Austria	1 July 2008
Poland	28 October 2014
Ireland	28 September 2018

Chilean observation sites

Although ESO is headquartered in Germany, its telescopes and observatories are in northern Chile. Here, the organisation operates advanced ground-based astronomical facilities:

• La Silla, which hosts the New Technology Telescope (NTT)
• Paranal, where the Very Large Telescope (VLT) is located
• Llano de Chajnantor, where ALMA, the Atacama Large Millimeter/submillimeter Array, is located

These are among the best locations for astronomical observations in the southern hemisphere. An ESO project is the Extremely Large Telescope (ELT), a 40-metre-class telescope. The ELT will be the largest visible and near-infrared telescope in the world.

Each year many requests are made for the use of ESO telescopes. Observations made with these instruments appear in many scientific publications annually.

La Silla

La Silla is located in the southern Atacama Desert 600 kilometres north of Santiago de Chile. It is the home of ESO's original observation site. La Silla is far from sources of light pollution and has one of the darkest night skies on Earth. In La Silla, ESO operates three telescopes: a 3.6-metre telescope, the New Technology Telescope (NTT) and the 2.2-metre Max-Planck-ESO Telescope.

The observatory also hosts national telescopes, such as the 1.2-metre Swiss and the 1.5-metre Danish telescopes.

Paranal

The Paranal Observatory is located atop Cerro Paranal in the Atacama Desert in northern Chile. Cerro Paranal is a mountain about 120 kilometres south of Antofagasta.

The observatory has several major telescopes: the four 8.2-metre telescopes of the Very Large Telescope, the 2.6-metre VLT Survey Telescope (VST) and the 4.1-metre Visible and Infrared Survey Telescope for Astronomy.

Llano de Chajnantor

The Llano de Chajnantor is a high plateau in the Atacama Desert, about 50 kilometres east of San Pedro de Atacama. The site is dry and not easy for humans, but good for submillimetre astronomy.

The telescopes here include the Atacama Pathfinder Experiment, and the Atacama Large Millimeter Array (ALMA). ALMA is a telescope for millimetre and submillimetre astronomy. This type of astronomy reveals parts of the universe that cannot be seen in visible or infrared light. It is ideal for studying cold clouds in space where new stars are born.

Outreach

The European Southern Observatory (ESO) has a team called the education and Public Outreach Department (ePOD). This team helps share astronomy with everyone.

ePOD also looks after the ESO Supernova Planetarium & Visitor Centre. It is a fun place to learn about space. It is located at the ESO Headquarters in Garching bei München and opened on April 26, 2018.

Video gallery

Here are some videos about the European Southern Observatory (ESO):

• ESO’s 50th-anniversary event (Munich Residenz in Germany, 11 October 2012)
• ESO’s first 50 years of exploring the southern sky
• José Manuel Barroso visits the ESO in January 2013
• Tim de Zeeuw talks on ESO and its 50th anniversary
• The temporary office buildings at the ESO headquarters in Garching being dismantled
• Timelapses of ESO’s VLT, ALMA and La Silla site