Light pollution threatens world's largest telescopes and darkest observatory, experts warn

The Giant Magellan Telescope (GMT) is a collaboration between international research institutions to build the world's largest optical telescope. (Image: ESO)

Astronomers are raising concerns about light pollution threatening Mount Paranal, home to the world-renowned Very Large Telescope (VLT). A proposed renewable hydrogen project in Chile could jeopardise the pristine night skies essential for advanced astronomical research.

Hydrogen Project Near Observatory Raises Alarm
AES Energy plans to construct a massive hydrogen production facility, INNA, just a few kilometres from Mount Paranal. The industrial park would include solar farms, wind farms, and hydrogen manufacturing units. Experts estimate the project could increase light pollution by 10%.

Mount Paranal offers unparalleled stargazing conditions, with clear skies 11 months annually. The VLT has achieved milestones such as imaging distant planets and uncovering the universe's cosmic web. However, increased brightness could degrade this location to an average observatory site.

On 28 April 2016, four powerful lasers, the most advanced ever installed on a telescope, illuminated the night sky over Chile's Paranal Observatory. These lasers, part of the European Southern Observatory's Very Large Telescope, created an artificial guide star as part of the new Four Laser Guide Star Facility. (Image: ESO)

ESO's Director General Xavier Barcons stressed the unique value of Paranal. "It’s the darkest place we’ve ever set an observatory," he said to Space.com. Moving the project 50 kilometres away could prevent disruptions, Barcons suggested.

Light Pollution Could Undermine Future Telescopes
The European Southern Observatory (ESO) is also constructing the Extremely Large Telescope (ELT) nearby. This $1.5 billion telescope, featuring a 130-foot-wide mirror, will study exoplanet atmospheres and distant galaxies. Experts warn the light pollution may hinder observing faint celestial objects.

ESO is calling for stricter protections for Chile's skies. While recent regulations limit stray light emissions, astronomers believe more action is needed to safeguard this critical region for science.

AES Chile stated the project remains in early stages and no investment decisions have been made. A public consultation will determine the project's future. For now, astronomers hope Paranal’s night skies remain untouched.