Light Pollution Threatens Astronomical Sites in Chile's Atacama Desert

The Atacama Desert in Chile is known for its clear night skies, offering views of stars, planets, and constellations visible to the naked eye. The region's dry climate, high altitude, and isolation from urban light pollution make it a key location for astronomical research.

It hosts major ground-based astronomical projects and attracts scientists from around the world. The president of the Chilean Astronomical Society stated that the Atacama Desert has more than 300 clear nights per year with no clouds or rain.

2025, an energy firm proposed a green power complex near the Paranal Observatory, managed by the European Southern Observatory (ESO). The site is also planned for the Extremely Large Telescope (ELT), a $1.5 billion project scheduled for completion in 2030.

The proposal was canceled in January 2026 after appeals from astronomers, physicists, and Nobel laureates. The incident highlighted concerns about existing sky preservation laws being insufficient. Several environmental regulations are now under review, including one from Chile's science ministry aimed at protected astronomical zones.

The director of the Cielos de Chile Foundation said the organization is working to ensure new criteria prevent impacts on astronomical areas. The foundation was established in 2019 to protect Chile's night skies.

The Paranal Observatory is one of nearly 30 astronomical sites in northern Chile, many managed by international organizations. These facilities use advanced instruments and contribute to research on the universe's origins. ESO's representative in Chile noted that ESO's telescopes are among the most powerful astronomical facilities on the planet.

An assistant professor at the University of Amsterdam reported that the selection rate for visiting astronomers at Paranal is 20% to 30%. The Atacama's terrain covers over 105,000 square kilometers, with altitudes exceeding 3,000 meters. These conditions support projects like the ELT, which will feature 798 mirrors and a light-gathering area of nearly 1,000 square meters.

An ESO astronomer stated that the ELT could help identify Earth-like planets in habitable zones. Over the past two decades, urban sprawl, industrial development, mining, and wind farms have altered the desert landscape. The director of the Astronomy Center at the University of Antofagasta recalled that the Atacama was once an ocean of darkness but has changed due to development.

He noted that a U.S. Smithsonian Institution solar observatory in Chile closed due to mining-related pollution. Scientists have warned that without updated regulations, similar development projects could arise. The potential impacts include increased light pollution, micro-vibrations, dust, and atmospheric turbulence, which could hinder astronomical observations.

“If you place the ELT next to a city, it doesn’t matter that its diameter is 40 meters long. It’s just the same as having a tiny telescope.”