Part 5/10:
Detecting alien signals hinges on the premise that an advanced civilization might be actively transmitting messages or beacons across space. The famous "Wow! Signal" of 1977 exemplifies this possibility: a 72-second, low-frequency signal with no natural explanation, which many consider a potential marker of extraterrestrial communication attempts. Since then, hundreds of similar signals have been recorded, most of natural origin but some still enigmatically unexplained.