Free Astronomy Magazine November-December 2020

31 NOVEMBER-DECEMBER 2020 ATMOSPHERIC POLLUTION whole Middle Ages (not very polluting, from our point of view) and reach the centuries that saw the birth and expansion of the Roman Empire, in particu- lar the centuries in which Rome dominated the an- cient world with its pres- ence on three continents. Even that long Roman pe- riod was characterized by intense mining activity, aimed at obtaining both silver (often used to mint coins) and lead (used in plumbing, paints and vari- ous furnishings). The production of lead, extracted mainly on the Iberian Peninsula, the Balkans, and the territories of Ancient Greece and Asia Minor, reached a peak of 80,000 tons per year during the golden age of the Roman Empire (2 nd cen- tury A.D.), a quan- tity comparable to that reached almost 2000 years later during the Industrial Revolu- tion. In addition to lead and silver, the Romans also produced large quantities of cop- per (up to 15,000 tons per year), which they often bound to tin to obtain the most resistant bronze. All this mining and metallurgical industriousness, in addition to being pollut- ing by itself, required a considerable con- sumption of wood and coal. Their combus- tion, producing the aforementioned carbon dioxide and sulfur dioxide, must have left even more clear traces than those of lead. Of these atmospheric pollutants from impe- rial Rome, however, no detectable deposits one million stars, which is an excessively large population for any SETI project that wants to observe single targets in search of unnatural signals sent to us after discover- ing the lead released into the atmosphere by the Spanish Empire. Can we now exclude even more ancient an- thropogenic traces, reaching even further into space today? No, we cannot. On the contrary, it seems that these traces exist, and to find them we have to fly over the D etails of the furnace, provisionally dated between the 1 st and 3 rd centuries A.D. [Archeologia Viva, Roma Events]