European Southern Observatory (ESO)ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organization in Europe and the world's most productive astronomical observatory. ESO provides state-of-the-art research facilities to astronomers and is supported by Austria, Belgium, the Czech Republic, Denmark, Finland, France, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO's main mission is to provide state-of-the-art research facilities to astronomers and astrophysicists.