Free Astronomy Magazine January-February 2022

5 JANUARY-FEBRUARY 2022 ASTRO PUBLISHING T wo articles published last Oc- tober 31 in Nature Astronomy dispelled any doubts about the terrestrial origin of a mysterious radio signal that seemed to come from the Proxima Centauri plane- tary system. The history and inter- pretation of that radio signal are quite interesting and deserving of our attention. It all started in April 2019, when a graduate student from the Univer- sity of Sydney, Andrew Zic, engaged in an observation program of Prox- ima Centauri, aimed at recording in different wavelengths the frequent flares that emanate from that star. Among the instruments used by Zic was the historic 64-meter-diameter Parkes Radio Telescope, operated by the Commonwealth Scientific and Industrial Research Organiza- tion (CSIRO) as part of the Australia Telescope National Facility (ATNF) radio telescope network. Since Prox- ima Centauri is a fundamental tar- get of Breakthrough Listen, a pro- gram of Breakthrough Initiatives dedicated to the search for alien technosignatures (evidence of tech- nologies attributable to extraterres- trial intelligences), some researchers involved in this project proposed to Zic and colleagues to join their ef- forts in radio observation of Prox- ima Centauri, with the plan to carry out SETI research in parallel with those studies of the stellar flares. Between April and May 2019, some series of observations were carried out in the frequency range between 700 MHz and 4 GHz, with a resolu- tion of just 3.81 Hz. This meant lis- tening to about 800 million radio channels simultaneously and conse- quently recording a huge amount of I n the background, the Parkes 64-Meter Radio Telescope, New South Wales, Aus- tralia, with the Milky Way on its right. [Daniel John Reardon] Above, a stunning time-lapse shows the Moon over Australia’s observatory at Parkes. [CSIRO]