The 1st intentional radio message to space was sent via Arecibo

Iconic Arecibo telescope is now slated for decommissioning. But its multi-faceted legacy will live on. In 1974, for example, Arecibo sent earthlings’ first intentional message to the cosmos. Source: https://earthsky.org/space/this-date-in-science-first-radio-signal-beamed-to-space…