For almost 60 years, efforts to pick up signs of extraterrestrial civilizations have yielded a big fat zero, but there have been plenty of false alarms to contend with.
To provide a reality check, the International Academy of Astronautics adopted a 1-to-10 rating system for claims of contact, known as the Rio scale, back in the early 2000s. Now a group of astronomers is proposing a “Rio 2.0” scale that brings the reality check up to date.
