One Hour of Satellite Streaks over Telescopes in Chile's Atacama Desert | ESO
This image shows satellites crossing the night sky above the northern Atacama Desert in Chile, over a period of just one hour. It is a stack of a time-lapse video taken on October 15, 2025 about two hours after sunset. A few streaks are caused by planes, and can be easily identified by their blinking-colored lights, but most trails are due to satellites.
A new European Southern Observatory (ESO) study has found that current proposals to launch over 1.7 million satellites into orbit, including extremely bright ones, would have “devastating consequences for astronomy.” According to the study, no more than 100,000 faint satellites, below naked eye visibility, should orbit Earth, to safeguard our ability to observe the night sky with modern telescopes. The study is the first to compute the extent to which large and bright satellite constellations would affect astronomical observations by making the night sky brighter.
Since 2019, the number of satellites orbiting Earth has increased rapidly, to over 14,000 today. Although if dead satellites and debris are included, the number of satellites currently in orbit rises to 32,000. SpaceX's Starlink telecommunications satellites represent the majority. Satellite proposals have also escalated in number and in potential impact. "Until now we have managed, but it's getting worse," stresses Olivier Hainaut. He has been involved in developing recommendations to mitigate the impact of satellite constellations on astronomy. While companies like SpaceX have taken measures to make their satellites less bright, current satellite proposals are going “beyond the limit” of what astronomy can withstand, he says. Hainaut, an astronomer at ESO for over 30 years, is the author of the peer-reviewed study on the impacts of satellite constellations accepted for publication in Astronomy & Astrophysics.
SpaceX plans to send one million more satellites into orbit, for space-based data centers. This would significantly alter the appearance of the sky. The new study shows that, for a large fraction of each night, hundreds of satellites would be visible and, at certain times, up to several thousand, similar to the number of stars seen with the naked eye in good conditions. Other planned satellite constellations such as E-Space's Cinnamon and China’s CTC-1 and 2 would add hundreds of thousands more satellites into orbit, compounding the problem.
Image Description: In the foreground, we see the dome of ESO’s Extremely Large Telescope (ELT), the world’s largest optical/infrared telescope, currently under construction atop Cerro Armazones. Behind it we see the lasers of ESO’s Very Large Telescope (VLT) at Paranal Observatory, 22 km away from the ELT. The background of this image shows a starry sky, including the bright lane of the Milky Way. Hundreds of bright streaks cross the sky in many directions, as if scratching the background natural sky behind it. The bottom of the image is occupied by the dark silhouette of a mountainous desert landscape. Atop the mountain at the center, is a small, distant metallic dome and yellow-orange lasers shine behind it.
Release Date: July 1, 2026
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