When newly graduated Karl Jansky joined Bell Laboratories in 1928, his first assignment was to determine the source of static that plagued transatlantic radio transmissions. Having built a rotating antenna, he found a radio signal emanating from the center of the Milky Way, in the direction of the constellation Sagittarius. On 5 May 1933 the New York Times reported Jansky’s discovery of “star noise.” The radio source later became known as Sagittarius A.
Although Jansky (1905–50) did not live long enough to learn the implication of his discovery, those radio waves were one of the first observational forays that later revealed the black hole sitting at the galactic center. The next decades yielded theoretical and observational results that explained radio emissions coming from distant galaxies and uncovered what lies at the heart of our own galaxy.
Reinhard Genzel, Andrea Ghez, and their collaborators provided experimental evidence that pinned down the...
