#OTD 20 March 1964, the #ESRO Convention was ratified – this date is now recognised as the birth of ESRO. Two years earlier, on 14 June 1962, 10 European nations had signed the convention to found this international space organisation. See https://t.co/8tOn9LI7HG pic.twitter.com/QXdONN7tIE

— ESA space history (@ESA_History) March 20, 2018