Whereas literature on satellites and outer space exploration has usually been dominated by vision, humankind’s initial encounter with the Earth’s first artificial satellite, Sputnik I, was overwhelmingly sonic. Tracking was originally enabled by the signal continuously transmitted by its radio beacon. Embedded in the International Geophysical Year (IGY) citizen science programs, radio amateurs played a crucial role in receiving the signal and assisting professional scientists in tracking the satellite in its initial phases. Their established existence as a distinctive worldwide community (...) of skilled operators and experimenters made hams special allies to IGY scientists and, in many respects, set them apart from other groups of amateur scientists. This essay focuses on radio amateurs’ practices and spaces of listening to Sputnik within the wider framework of the IGY. In transcending national and terrestrial boundaries, Sputnik’s signal shaped new spatialities at a variety of scales: from the macroscales of the globe and outer space to the intimate microscale of the domestic radio shack. Focusing on radio amateurs’ personal experiences and on the invisible agencies of Sputnik’s signal, the essay uses sound as a way into the sociocultural, political, and scientific importance of the IGY. More broadly, it contributes to a multisensory history (and geography) of science. (shrink)