Invisible dark matter governs the rotation of galaxies — Vera Rubin showed back in the last century that stars move as if pushed by an unseen force. One of the prime suspects is the dark photon, a massive cousin of ordinary light, predicted by the extended equations of Maxwell and not fitting into the Standard Model.

Scientists turned the planet into a giant radio receiver. The space between Earth and the ionosphere (the electrically charged layer of the atmosphere) forms a resonator that greatly amplifies magnetic tremors if their frequency matches the 'radio wave' of a dark photon. It's like one guitar string resonating to a note played on another. Years-long magnetic field records enabled a delicate spectral analysis — fishing out a single frequency from the noise.

For the first time, air conductivity was taken into account, refining the calculation and helping to separate a possible signal from interference. They didn't hear a direct 'hello' from dark matter, but they set the strictest limits on its interaction with magnetism — for a mass range from 10⁻¹⁵ to 2×10⁻¹³ eV. And the sought frequencies below 100 Hz, where whales sing and power lines hum, force scientists to scrub the sounds of the ocean and civilization from the data.