Claudius Ptolemy was a Greek mathematician, astronomer and geographer who lived in the Egyptian city of Alexandria while under the rule of the Roman Empire. Much of medieval astronomy and ...

Claudius Ptolemy, more commonly known just as Ptolemy, was a Greek cartographer born at the ... Ptolemy was also an astronomer, a chemist, and a mathematician. A well-rounded man of science ...

In accord with the Greek ideals of symmetry and harmony, geographer and astronomer Claudius Ptolemy declared that a great northern landmass must be balanced by a twin in the Southern Hemisphere.