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 — which have also raised concerns about their impacts on health and the environment — would affect astronomical observations by making the night sky brighter.