Ancient scientists accomplished prodigious feats by obtaining some preliminary estimates of the size of our planet and the distance to the most important stars. Their work stimulated the generations that followed them, equipped with better mathematical tools and more precise instruments, who nevertheless faced a difficult logical puzzle: there is a curious symmetry in the measurement of the sky and that of the Earth. To determine the geographical position, the distance between two locations or even the size of the Earth itself, it was essential to make measurements of the stars, such as finding the height of a star. But this relationship was reciprocal, and estimating the position and distance to the stars was only possible through measurements that had the Earth itself as a measuring standard or by knowing in detail the distance between two observation sites. Precision geography was not possible without astronomy, and vice versa.