The increase of satellites in Earth’s orbit is reaching unprecedented levels. Since 2019, the number has surged from a few thousand to over 14,000, driven primarily by communication networks like Starlink. According to a recent study by the European Southern Observatory (ESO), however, the proposed developments could fill space beyond our current understanding.
Plans are underway for more than 1.7 million additional satellites. Researchers warn that this could have “devastating consequences for astronomy.” To ensure enduring scientific observations, they believe the number of dim satellites in orbit should not exceed 100,000.
“So far, we have managed the situation, but it is becoming increasingly critical,” states ESO astronomer Olivier Hainaut. Despite individual companies taking measures to reduce the brightness of their satellites, the current expansion plans exceed “the limits of what astronomy can withstand.”
Thousands of Lights Instead of Stars
SpaceX’s plans are particularly ambitious: they aim to launch around one million additional satellites for space-based data centers. This is alongside initiatives from other operators such as E-Space with their Cinnamon project, and the Chinese systems CTC-1 and CTC-2.
With new simulations, hundreds, and at times even thousands of satellites would be visible simultaneously throughout most nights. They could numerically rival the stars that can be observed under optimal conditions.
A more negative view appears in the study regarding the concept of the US startup Reflect Orbital. Their mirror-like satellites are designed to direct sunlight onto Earth and create light beams with at least a five-kilometer diameter; a fleet of 50,000 satellites is planned by 2035.
Mirrors Brighter than the Full Moon
Hainaut’s calculations indicate that within such a light beam, a satellite could appear up to four times brighter than the full moon. Even outside the beam, each object would be as bright as Venus. In heavily light-polluted cities, these satellites could be the only distinctly visible light points in the sky.
This situation poses significant research dilemmas. “Sunlit satellites are many times brighter than distant galaxies,” explains Hainaut. “When a satellite crosses our field of view, it leaves a bright streak on the image, obscuring everything behind it.”
Simulations show that at the Very Large Telescope (VLT) of the ESO in Chile, numerous satellite trails would appear on virtually every capture. Especially sensitive wide-angle cameras could render most images useless during several hours of the night.
In addition to the visible trails, satellites also degrade the overall quality of the night sky. Dimly lit objects create a diffuse light veil, while brighter satellites scatter light across the atmosphere. This significantly increases background brightness, hindering the observation of faint galaxies, Earth-like exoplanets, or potentially dangerous asteroids.
Researchers therefore urge for a limitation on the number of satellites and the construction of as many dim satellites as possible. “Low Earth orbit is a cosmic coastline,” Hainaut summarizes. “We must regulate the ecological and visual footprint of these megaconstellations.”
Article Reference
O. R. Hainaut. (2026). Large or bright satellite constellations Effects on observations, including on the background sky brightness.
