The European Southern Observatory (ESO) celebrates 60 years!

On October 5, 1962, five countries – Belgium, Germany, France, the Netherlands and Switzerland – began what has become the largest international collaboration of ground-based observatories: European Southern Observatory (ESO).

Currently, cooperation with more than 16 European countries, strategic partnership of Australia and Chile’s hospitality and research areas: research centers in Germany (Garching bei München) and Chile (Santiago). It also has a team of close to 1000 people from different countries, including astronomers, engineers, journalists and others, serving more than 22,000 people with the world’s largest and best telescopes.

Speaking of telescopes, all ESO telescopes are terrestrial, meaning they are on the ground, not satellites, and are located in the Atacama Desert. But why Chile? The country has the best conditions for observation from the ground. Several factors can interfere with professional astronomical observations, particularly atmospheric factors.

Therefore, being in high, remote places with a dry atmosphere is essential, and the Atacama Desert has all these qualities. By placing the telescopes in high places, there is less air mass in the observation path. It’s like being in a swimming pool: the deeper you go, the more water there is between you and the atmosphere.

In observations, on the other hand, we want to go very high so that there is minimal air between the telescopes and the Universe. Another important factor is light pollution, both artificial and natural. It is pitch dark that is important during observations.

Therefore, these telescopes need to be placed as far away from civilizations as possible. A final factor that makes Chile one of the best observation spots is that in a dry atmosphere there is less turbulence in the path of the light, guaranteeing better quality observations.

ESO has 3 observation sites in Chile, La Silla, Paranal and Chajnantor. La Silla was ESO’s first observatory and is home to two of the world’s most efficient 4-metre telescopes. Paranal is home to the Very Large Telescope (Portuguese for “very large telescope”, VLT), one of the most advanced optics telescopes available today, consisting of 4 units with 8.2 meters diameter mirrors. .

In addition, with the help of other small telescopes, the 4 units can work together to create an interferometer with a virtual mirror size of 200 meters! So, instead of making a 200-metre mirror, which has physical limitations, we can combine several small telescopes to achieve the same resolution capability.

Finally, Chajnantor hosts the ALMA and APEX arrays, two sets of antennas that observe wavelengths in the millimeter and submillimeter range with the best accuracy in the world.

Finally, ESO is building the Extremely Large Telescope (ELT), the “biggest eyes on Earth”. When ready, the ELT will be a 39 meter diameter reflecting telescope. Therefore, it is the largest mirror ever built for observing in the optical and near-infrared ranges.

Brazil becomes first non-European ESO member

In 2010, with the rise of science and astronomy in Brazil, it became the first country from outside Europe to be invited to join ESO. As part of the agreement, the country can enjoy the benefits of cooperation on equal terms with other member states; this includes, for example, Brazilian industries involved in telescope construction and prioritizing Brazilian astronomers in observing time.

In 2015, the agreement was ratified at the Brazilian National Congress on May 14. But Brazil never brought the deal to an end. With the political instability in the country, European cooperation decided to suspend the invitation to Brazil in 2018.