1. Unusual Radio Signals
One of the most tantalizing signs scientists look for are unusual radio signals that stand out from the cosmic background. These signals, like the famous ‘Wow! signal’ detected in 1977, often feature patterns or frequencies that don’t match known natural sources. Researchers continue to monitor the skies for bursts, pulses, or narrow frequency bands—any hint that could point to a technologically advanced civilization reaching out across the stars.