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The rapid increase in the number of satellites in Earth’s orbit is no longer just a technical curiosity but is becoming a serious environmental concern. International teams of scientists, including experts from the Slovak Academy of Sciences (SAS), warn that commercial space activities are fundamentally altering the natural cycle of light and darkness, with negative impacts on human health, ecosystems, and astronomical research.

The scientific community is raising concerns about the dynamic growth of commercial space activities. Researchers from the Slovak Academy of Sciences and Comenius University in Bratislava contributed to a study introducing a new model for analysing space-based light pollution. Results published in April 2026 indicate that expanding satellite constellations, such as those operated by SpaceX, along with plans to illuminate the Earth from orbit intentionally, could permanently disrupt the natural night environment globally.

The issue is not only the growing number of objects in orbit, which may reach millions, but also the scattering of sunlight by space debris. This phenomenon increases the overall brightness of the night sky and brings several risks:

· Health and nature: Disruption of natural darkness affects human biological clocks (circadian rhythms) and alters the behaviour of migratory birds and nocturnal animals.

· Astronomy: Satellites interfere with optical and radio observations, degrading the quality of scientific data collected by telescopes.

· Technological developments: Concepts such as reflective satellites (e.g., Reflect Orbital) are emerging, which could artificially illuminate parts of Earth at night.

The latest research, involving Miroslav Kocifaj and František Kundracik from the Slovak Academy of Sciences and the Faculty of Mathematics, Physics and Informatics of Comenius University, makes a significant contribution to understanding this phenomenon. The newly developed model enables detailed analysis of how satellites and space debris contribute to light pollution.

“Our results show that light pollution is more complex than previously assumed. To effectively protect the night environment, we must consider not only terrestrial light sources, but also the growing number of objects in orbit,” says Miroslav Kocifaj from the Institute of Construction and Architecture SAS.

The scientists also stress that the light conditions that have shaped life on Earth for millions of years are changing too rapidly. They call on international regulatory bodies, such as the Federal Communications Commission (FCC) in the United States, to thoroughly assess environmental impacts when approving new satellite networks. The

improved modelling developed by the Slovak team now enables better planning for protecting migration routes and sensitive ecosystems.

Prepared by: Jozef Bednár