Astronomers are cautioning that the loss of the inherent natural quality of the night sky worldwide will become an unprecedented global threat to cultural and natural heritage, as well as future economic benefits.
Light pollution poses a threat to the natural world
Astronomers have alerted to the light pollution caused by the increasing number of satellites orbiting the Earth, which is creating a “previously unseen threat to nature” on a global scale.
In a series of studies published in the journal Nature Astronomy, international astronomers reveal that the number of satellites in low Earth orbit has more than doubled since 2019 when the US-based company SpaceX launched a large-scale “constellation” of thousands of satellites for the first time.
New batches of internet satellites have also been planned for early deployment, adding thousands more satellites to the already densely populated region of satellites, less than 2,000km from Earth.
Astronomers also point out that with each new satellite appearing in low Earth orbit, the risk of collision with another object orbiting the Earth increases, resulting in more debris.
This could create a chain reaction where consecutive collisions occur, generating even smaller fragments that contribute to the “space debris cloud” reflecting light back to Earth.
Impact on astronomical activities
In a study, astronomers have identified for the first time the financial and scientific impact of a brighter night sky on the operations of a large astronomical observatory.
The Increasing Number of Launched Satellites Leads to Escalating Light Pollution – Illustration: NASA
Specifically, through simulations, astronomers determined that for the Vera Rubin Observatory under construction in Chile, the darkest portion of the night sky in the next decade will be brighter by 7.5% compared to the present, which means that the number of stars observable by Vera Rubin will decrease by 7.5%.
This necessitates an extension of nearly 1 year to the surveying process of this astronomical observatory, resulting in an additional cost of $21.8 million.
John Barentine, co-author of the study and affiliated with the US-based Dark Sky Consulting Company, also warns of another incalculable consequence, which is the astronomical phenomena that humans will never be able to observe due to a brighter night sky.
Researchers also caution that a brighter night sky not only affects astronomical observations but also threatens the “ancient relationship between humans and the night sky”.
Astronomer Aparna Venkatesan at the University of San Francisco emphasizes, “The universe is a shared heritage and ancestor of humanity, connecting us through science, art, stories, and cultural traditions—and now the universe is in danger.”
Given this situation, a group of astronomers in Spain, Portugal, and Italy are calling on the scientific community to “prevent the assault” on the night sky by restricting satellite launches into Earth’s orbit.