that the earth is a sphere was established by hellenistic astronomy in the 3rd century bc. the terrestrial globe appeared in that period. now, there are no terrestrial globes from classical antiquity or the middle ages in existence. the first example of terrestrial globe known was the one the ancient greek crates of mallus made in the middle of the 2nd century bc. the greek geographer strabo wrote about crates's terrestrial globe during the early years of the roman empire.