In the early centuries of astronomy, however, our visions of the cosmos often took the shape of diagrams—representing what we believed about our solar system. Ptolemy’s Geocentric Universe.

In the text, Ptolemy advised constructing an instrument that was no smaller than about 1 foot (0.3 meter) in diameter, according to the study.

Melvyn Bragg and his guests discuss the last of the great Greek astronomers of antiquity, Ptolemy, and his influence on ancient and medieval astronomy. Show more Melvyn Bragg and his guests ...

To get elephants, Ptolemy’s army looked to what is now Eritrea. Today, elephants in Eritrea are rare, numbering only 100 to 120. The population lives near the border with Ethiopia, ...