His main astronomical work , the Almagest , was the culmination of centuries of work by Hellenic , Hellenistic and Babylonian astronomers .
The Ptolemaic system , developed by the Hellenistic astronomer Claudius Ptolemaeus in the 2nd century AD finally standardised geocentrism .
Ptolemaic 's main astronomical work , the Almagest , was the culmination of centuries of work by Hellenic Hellenistic Hellenistic and Babylonian astronomers .
The Ptolemaic system , developed by the Hellenistic astronomer Claudius Ptolemaeus in the 2nd century AD finally standardised geocentrism .