The Atacama Desert adds a strategic piece to its astronomical map: it is an observatory that will mark a before and after in the exploration of the high-energy universe.
The largest gamma-ray hunt ever undertaken will have its southern epicenter in Paranal, where on December 17, 2025, the first stone of the Cherenkov Telescope Array Observatory (CTAO) was laid.
The facility will be located 10 kilometers southeast of the Paranal observatory.
There it will complete the scientific ecosystem that already includes the Very Large Telescope and prepares the Extremely Large Telescope.
Xavier Barcons, Director General of the European Southern Observatory (ESO), highlighted that Paranal is “a place with the most pristine skies“.
How gamma-ray detection works in the Atacama Desert
Gamma rays do not reach the ground like visible light. When a gamma photon enters the Earth’s atmosphere, it triggers a cascade of particles that produces a very brief flash of Cherenkov radiation.
That signal, which lasts just a fraction of a second, allows the reconstruction of the original event.
The CTAO will cover an energy range from 20 gigaelectronvolts to 300 teraelectronvolts. These levels exceed the energy of visible light by billions of times.
To achieve this, the observatory will employ three types of telescopes optimized for different sections of the spectrum.
The planned configuration in the south will exceed 50 telescopes. This instrumental density represents a scale leap compared to current gamma-ray observatories.
What cosmic phenomena will be studied
The new observatory will pursue signals associated with extreme processes in the cosmos. Its scientific program is organized into three major areas:
- Investigate the origin and role of relativistic cosmic particles
- Probe extreme environments such as black holes and neutron stars
- Explore the frontiers of physics with indirect searches for dark matter
The high-energy universe functions as a natural laboratory. There, matter and radiation reach conditions that no terrestrial experiment can reproduce comparably.
Gamma rays complement the detection of gravitational waves and neutrinos.
This multi-messenger astronomy allows for the interpretation of violent and transient events with greater precision. The CTAO will provide that layer of information in a coordinated framework with other facilities.
A project with global dimension
The CTAO will be deployed in two locations. One in Chile and another in La Palma, at the Roque de los Muchachos Observatory.
This “two skies” architecture allows for continuous observation and covers the entire firmament.
The start of the foundation work involves a consortium of local companies. The first telescopes will be operational before the end of 2026.
“We are now turning a dream into reality,” said Stuart McMuldroch, General Director of the CTAO.
The observatory will generate hundreds of petabytes per year. It will operate under open science principles, with public access to high-level scientific products.
The model reserves 10 percent of observation time for Chilean scientists.
Chile thus consolidates its position as a global astronomy hub. The CTAO places infrastructure in Atacama that connects fundamental research with advanced technological capabilities.
From ultra-fast cameras to large-scale data processing systems.
