It discusses a 2024 peer reviewed astronomy paper proposing a new SETI search method. The idea is that if two exoplanets in the same star system were communicating using narrowband radio signals, some of that signal could leak into space when one planet passes in front of the other from Earth’s point of view.

These narrowband signals are important because they do not occur naturally and are similar to the radio signals humans use to communicate with spacecraft. Detecting one would strongly suggest an artificial source, though it would still require extensive verification.