Excerpt:

Astronomical radio sources, while intrinsically intense, are also far away. What little of their signal reaches Earth is therefore really faint: A single mobile phone on the surface of the Moon would outshine all but the very brightest of them.

Communication signals of Earth-orbiting satellites are much stronger but are by regulation limited to certain wavelengths. They’re also known to radio astronomers, who can filter them out. However, leakage radiation may result in artificial signals at unintended wavelengths. Leakage typically comes from human activity on the ground, but with the number of satellites literally skyrocketing, astronomers are becoming concerned about the effect from space. Now, a team has announced the first detection of this electromagnetic interference from satellites.

“Leakage radiation from artificial satellites as a possible interference first appeared in our minds only about two years ago,” recalls Benjamin Winkel (Max-Planck Institute for Radio Astronomy, Germany, and Committee on Radio Astronomy Frequencies, France). “Back then, nobody knew how strong such an effect would be, and if this was more than just a theoretical problem.”

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