Free Astronomy Magazine November-December 2020

30 NOVEMBER-DECEMBER 2020 ATMOSPHERIC POLLUTION civilization 450 light years (or less) from Earth. Theo- retically yes, but only if it has much more powerful in- vestigation instru- ments than ours. It is estimated that, within a sphere of space with a radius of 450 light-years around the Earth, there are at least technique, introduced forty years after the overthrow of the Inca Empire, consisted of reducing the galena ore to powder and adding mercury, which amalgamated with the silver and separated it from the waste material (a subsequent distillation allowed for the recovery of the silver). Both tech- niques had dramatic effects on the environ- ment, as galena is made up of almost 90% lead and only 1-2% silver. Consequently, the smelting and, above all, the pulveriza- tion of that mineral during the Spanish oc- cupation introduced increasing quantities of lead and other harmful elements into the South American atmosphere, to the point of making that long period of in- tense mining and related metallurgical ac- tivity easily recognizable in the ice cores extracted from the Quelccaya Ice Cap (Peru), the second largest glaciated area in the tropics. This glacial site is located about 800 km away from Cerro Rico de Potosí (Bo- livia), the largest silver mine in the world and the one that some studies indicate as the point of origin of the metals found in the Peruvian ice. The distance between the two locations gives an idea of the level of pollution that affected those territories in the second half of the sixteenth century (and even later). At this point it is legitimate to ask oneself whether the anthropogenic trace of lead relating to that period can be observed “today” by a hypothetical contemporary A t the begin- ning of 2019, one of the oldest furnaces used by the Romans was found in the gar- dens of Palazzo Corsini, located in the center of Rome. [Archeolo- gia Viva, Roma Events]