6. The Biggest Problem: Earth’s Own Signals

6. The Biggest Problem: Earth’s Own Signals
Earth is filled with radio-frequency interference from satellites, aircraft, radar, communication systems and electronic equipment. These sources can imitate a signal from space.
A famous example is BLC1, a narrowband signal detected in observations toward Proxima Centauri. After detailed analysis, the Breakthrough Listen team concluded that it was a product of human-made interference, not an extraterrestrial transmitter. This demonstrated why exciting candidates require repeated observation and independent confirmation. Breakthrough Listen analysis
A credible detection would need to:
Persist or repeat in follow-up observations.
Track a precise position in the sky.
Exhibit behavior consistent with an astronomical source.
Survive detailed checks for satellites and terrestrial equipment.
Be confirmed independently by another observatory.