Free Astronomy Magazine May-June 2025

46 MAY-JUNE 2025 ASTRO PUBLISHING skies and protect as- tronomy for future generations is to relo- cate the INNA com- plex.” Furthermore, INNA’s infrastructure is likely to encourage the development of an in- dustrial hub in the area, which could turn Paranal into an unus- able site for top-level astronomical observa- tions. “ESO and its Member States are fully sup- portive of energy de- carbonisation. For us Chile should not have to make a choice be- tween hosting the most powerful astro- nomical observatories and developing green- energy projects. Both are declared strategic priorities by the coun- try and are fully com- patible — if the different facilities are located at sufficient distances from one another,” says ESO Direc- tor General Xavier Barcons. The full technical report was submit- ted to the Chilean authorities in late March, as part of the Citizen Partici- patory Process (CAP) in the environ- mental impact assessment of INNA, and made public ahead of the 3 April deadline. In addition to this press release, ESO has made public in advance an executive summary of the report. “We are extremely grateful for the support we’ve received from the Chilean and worldwide research communities, and from our ESO Member States. We also thank the Chilean authorities for looking into this matter. We are more committed than ever to working together to protect the irreplaceable Paranal skies,” concludes Barcons. F lorentin Millour captured this breathtaking wide-field image of comet C/2024 G3 (ATLAS) on January 21 from ESO’s Paranal Observatory in Chile. The Very Large Telescope sits atop Cerro Paranal to the left, while the comet sets in the western horizon right after sunset. [F. Millour/ESO] The technical analysis looked into other impacts from the project, such as the increase in atmospheric turbu- lence, the effects of vibrations on the delicate telescope equipment, and dust contamination of the sen- sitive telescope optics during con- struction. All of these would further deepen the impact of INNA on Paranal’s capabilities for astronomi- cal observation. In addition to the dark and clear skies, Paranal Observatory is the world’s top site for astronomy thanks to its exceptionally steady and stable atmosphere – it has what astronomers call excellent seeing conditions or very low “twinkling” of astronomical objects caused by turbulence in Earth’s atmosphere. With INNA, the best seeing condi- tions could deteriorate by up to 40%, in particular due to the air tur- bulence caused by the project’s wind turbines. Another worry is the im- pact of the vibrations caused by INNA on the VLT Interferometer (VLTI) and the ELT, which are both extremely sensitive to micro-seismic noise. The technical analysis reveals that INNA’s wind turbines could pro- duce an increase in these micro-vi- brations of the ground that is large enough to impair the operations of these two world-leading astronomi- cal facilities. Dust during construc- tion is also problematic as it settles on the telescope mirrors and ob- structs their view. “Taken together, these disturbances seriously threaten the current and long-term viability of Paranal as a world-leader in astronomy, causing the loss of key discoveries about the Universe and compromising Chile’s strategic advantage in this area,” says de Gregorio-Monsalvo. “The only way to save Paranal’s pristine !