Now we need to look back in time to the classical understanding of the world. How better to do that than with Ptolemy's map of the world known to him at the time? None of Ptolemy's maps survived into the medieval world, but his list of places - a sort of gazetteer - did. 8000 places with his estimates of their latitude and longitude, from which his maps have been reconstructed. See the similarity? No, nor do I, but Schiaparelli found a way to link them. #maps#Mars#Ptolemy