Scientists study 100 possible alien radio signals from collapsed Arecibo Observatory, ending groundbreaking 21-year search

Scientists completed a groundbreaking 21-year search for alien radio signals using data from Puerto Rico's collapsed Arecibo Observatory, with over 2 million citizen volunteers helping analyze 12 billion signals through the SETI@Home project. After narrowing down candidates to 100 promising sources, researchers found no evidence of extraterrestrial transmissions but established new sensitivity levels for future alien-hunting efforts.