Over 1.7 million new satellites in Earth orbit could render night sky observations unusable for astronomers, according to a study by the European Southern Observatory (ESO). The research, led by astronomer Olivier Hainaut, calculates that satellite constellations will increase night sky brightness, obstructing telescopic views of distant galaxies and exoplanets.
How Satellite Constellations Outshine Celestial Objects
Hainaut’s simulations, based on data from ESO’s Very Large Telescope (VLT) and the Vera C. Rubin Observatory, reveal that SpaceX’s planned 1 million satellites will alter the appearance of the sky. Reflect Orbital’s 50,000-satellite project, set for 2035, could make each satellite four times brighter than a full moon.
“Satellites illuminated by the Sun are much brighter than distant galaxies. When a satellite crosses what we observe, it makes a bright streak in our image, altering what is behind,” Hainaut explained.
The Environmental and Ecological Consequences
The study also highlights indirect impacts. Satellite launches have direct impacts on air quality, while re-entering satellites cause pollution when they burn up in the atmosphere. ESO’s analysis found that 32,000 satellites, including inactive ones or their remains, orbit Earth, with 14,000 active.
Technical Thresholds for Astronomical Viability
Hainaut’s model establishes a critical threshold: no more than 100,000 satellites with low luminosity, below visibility to the naked eye, should orbit Earth to preserve modern telescope capabilities.
Industry Responses and Regulatory Challenges
Reflect Orbital’s satellites, designed to reflect sunlight to Earth, face scrutiny over their potential to make the night sky present with hundreds of very bright satellites visible to the naked eye.
Impact on Scientific Research and Public Perception
Observatories in light-polluted cities like Munich could see satellites as their only “stars” visible in the night sky. This threatens professional research and public engagement with astronomy.
Technical Solutions and Policy Directions
The ESO study serves as a technical roadmap for policymakers, emphasizing the consequences for astronomy.
