During the Cold War, at about the time Ian Fleming was penning From Russia with Love (1957), the Soviet Union stunned the world with a successful launch of an artificial satellite, Sputnik. While Western and Soviet spies, real and fictional, were hatching plans to acquire field and signals intelligence, the world’s scientific community helped to create their own daring initiative. The International Geophysical Year (IGY) of 1957–58 was audacious in scope and scale – scientists around the world were going to explore and interrogate outer space, the polar regions, and the oceans, and share the ensuing data for the sake of global knowledge generation.

We review the progress in geomagnetic research for the century preceding the founding of IAGA’s predecessor in 1919. We then discuss the contributions of IAGA to the development of the study of geomagnetism and aeronomy during the past 100 years, as illustrated by the marked expansion in the number and geographic coverage of magnetic observatories. IAGA has led efforts to develop geomagnetic indices, reference fields, magnetic anomaly maps, and to rapidly distribute magnetic data. It played a key role in the establishment of aeronomy as a separate scientific discipline. IAGA has fostered the coordination of paleomagnetic data bases and was an early advocate of the investigation of Sun-Earth relationships. IAGA flagship efforts since 1919 years include support to the highly-successful International Geophysical Year (IGY) in 1957–1958 and more recently to the IGY 50th-year commemorative programs of the International Heliophysical Year (IHY) and Electronic Geophysical Year (eGY).