Before it was seen, it was heard. In the early 1930s, a Bell Labs engineer named Karl Jansky was given the job of sorting out where the static interference in radio transmissions came from. With an ungainly but ingenious steerable antennarnhe tracked a number of sources. Most were thunderstorms, but one wasn't. As Jansky tracked it across the sky from day to day he realized that it was far beyond Earths atmosphere, and indeed beyond the Solar System — an abiding hiss from somewhere in the constellation of Sagittarius.
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