ESO, the European Southern Observatory, Garching near Munich and Telescope in Chile



The European Southern Observatory (ESO) was built in 1962 in Garching near Munich for the purpose of building, equipping and operating astronomical observatories in the southern hemisphere as well as for the purpose of encouraging and organising European cooperation initiatives in the field of astronomy research.

ESO’s member countries are Austria, Belgium, the Czech Republic, Denmark, Finland, France, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom.

Today, the ESO is at the main institution for European astronomy research. ESO research activities are mainly conducted by guest astronomers from member states in all fields of modern astrophysics. The ESO delivers at least rudimentary answers to fundamental questions regarding the origins and future of the universe.

ESO observatories are in unique locations in the Chilean Atacama Desert, where the most modern and competitive observation facilities are made available to European astronomers:

Together they form the world's most powerful optical telescope: the four mirrors of the Very Large Telescope (VLT)

The ESO's La Silla Observatory includes half a dozen medium-sized optical telescopes (including the Swiss 1.2 m Leonhard Euler Telescope, which was built and is operated by the Geneva Observatory).


Comprised of four identical unit telescopes with 8.2m mirrors, the Very Large Telescope (VLT) is housed in the Paranal Observatory. The combination of these four mirrors makes the VLT the world's most powerful optical telescope: the VLT Interferometer (VLTI) allows objects in space to be seen with a resolution 25 times higher than that of any one of the main telescopes.

The first eight radio telescopes of the intercontinental project ALMA at 5,100m above sea level

The ESO also participates in the international Atacama Large Millimetre Array (ALMA) project – a network of 64 radio telescopes, each with a diameter of 7-12 metres, located on the Chajnantor Plateau at an altitude of 5,100 m. ALMA was inaugurated as a partnership with North America and Japan in 2013, although the first scientific observations had already begun in 2011 using part of the facility.

Work on the next ambitious follow-up project has already begun:

The Extremely Large Telescope (ELT), an optical 39-metre telescope with a main mirror comprising 798 hexagonal segments, a secondary mirror with a diameter of 4 metres and another three mirrors that form the adaptive optics for stabilising the image.

The ELT will be more than 100 times more sensitive than the VLT, making it the largest telescope in the world for visible and near infra-red light. Construction at the site on the Cerro Armazones began in 2014, and initial observations should be possible in 2027.

Swiss participation

Swiss membership to the ESO provides Swiss astronomy researchers with access to the entire ESO infrastructure.

Thanks to the outstanding quality of our own astronomy institutes (Bern, Geneva, Lausanne and Zurich), which are able to make the most of Swiss participation in the ESO (and the ESA in the field of space astronomy), Swiss astrophysics research enjoys a strong international reputation. Research activities range from the search for planets outside our solar system to exploring stars and galaxies of the universe.

Swiss businesses and institutions also have the opportunity to contribute know-how and technology (in particular high-tech) to the ESO facilities. Parties interested in the ESO invitations to tender should contact the Swiss ILO Office.

Switzerland's membership contribution to the ESO is around 4.5% of the total budget of CHF 215 million. Through its participation, Switzerland makes an active contribution to the further development of the organisation's infrastructure.


SERI, Kevin Reymond
Head of the Swiss delegation to ESO Council

Prof. Francesco Pepe
Scientific delegate representing Switzerland

SERI, Astrid Vassella
Swiss representative in the ESO Finance Committee