Astronomers are becoming increasingly concerned about the growing number of satellites that are lighting up the night sky by reflecting sunlight to Earth. In 2022, the prototype communications satellite BlueWalker 3 was launched and it is now the brightest commercial satellite ever – outshining almost every star in the sky. And to make matters worse, communications satellites like BlueWalker 3 broadcast microwave signals that can interfere with radio astronomy.

To talk about the threats to astronomy posed by satellites I am joined down the line by the radio astronomer Mike Peel, who is at Imperial College London and Jeremy Tregloan-Reed of Chile’s University of Atacama, who studies the cosmos using visible light.