In Chile, the observation of one of the most starred skies in the threatened world

The night falls on the Atacama desert and four powerful telescopes are starting to scrutinize one of the purest and most starred skies in the world. However, the Paranal Observatory, in northern Chile, could be threatened by the light pollution of an energy megaproject.

Located 2,635 meters above sea level, the site allows“Observe the Milky Way with unequaled clarity (…), these are the most clear, darkest skies”explains to AFP Itziar de Gregorio, a Spanish astronomer from the Austral European Observatory (ESO), who operates the premises.

A few kilometers from this “Global astronomical sanctuary” However, the construction of a factory dedicated to clean energies is planned, as part of the ambitious Chilean program for replacing fossil fuels by 2050.

Scientists are concerned about the light pollution that the project could generate: excess artificial light limits the visibility of certain phenomena, such as eclipses and meteorite rains, they warn.

This phenomenon, generally linked to an increase in public lighting and the presence of luminous advertising panels, also affects sleep cycles in humans and disorients migratory birds. However, it often goes unnoticed.

“When you see an open tap, you realize that you lose water. But if we see a very lit place at night, we don’t think it’s pollution ”notes Daniela Gonzalez, of the Cielos de Chile Foundation, which fights against the scourge.

A Paranal, it is when the sun sets that the most intense phase of work begins. During the day, astronomers and engineers process the data. At night, they probed the infinity.

Ici, “Research focuses on almost all the phenomena of space”like the planets and comets close to the earth, black holes and life out of the solar system, enthuses Steffen Mieske, the chief of scientific operations of the site.

Zone d’“Bright exclusion”

In the Atacama desert, the most arid and driest in the world, the clouds are rare, offering ideal conditions for the observation of the cosmos. In addition, light pollution is low. The Paranal Observatory is thus more than 100 km from Antofagasta, the nearest city.

But that could change with the construction of the new factory. In an open letter, around forty astronomers, scientists and even poets have recently expressed their concern.

The project, funded up to $ 10 billion per AES Andes, the Chilean subsidiary of the American company AES Corporation, would extend over 3,000 hectares. According to the company, it provides “The production of hydrogen and green ammonia, as well as the development of solar, wind and storage of batteries”.

However, the question of the distance between the paranal observatory and the future factory divides. While the company estimates it at 20 or 30 km, the researchers estimate that it does not exceed 11 km. Without opposing the project, the latter demand the creation of a zone of“Bright exclusion” in order to preserve the integrity of the site.

AES Andes, in a short press release, assures that his project respects “The highest standards in terms of lighting” And responds to that enacted by the government on the subject. Established in October, the latter aims in particular to protect the main places of astronomical observation.

“Window on the universe”

The project, currently under environmental assessment, should not receive its operating license before two to three years.

In the Cerro Armazones mountains, about twenty kilometers from the observatory, the construction of the European giant telescope (Elt) is progressing. It is the largest optical instrument in the world with 39 meters in diameter.

For scientists, the risk is also that the energy megaprojet interferes with the operation of this device, the launch of which is planned in 2028.

Invaluable for astronomical research, “Window on the universe” What does Chile represent, warns Itziar de Gregorio. An increase in light pollution in this single site could delay “The answer to which we aspire so much (…), know if we are alone or not in the universe”alerts the astronomer.