CLASSIC STUDY TOOK PREVIOUS KNOWLEDGE FROM EGYPTIANS AND BABYLONIANS AND COMBINED THIS WITH THEIR GENIUS OF MATHEMATICS TO FORM BASIC ASTRONOMICAL STUDIES AND THEORIES. MANY STILL VALID TODAY. PYTHAGORAS, PLATO, HERACLIDES OF PONTUS, HIPPARCHUS AND OTHERS. SPHERICAL EARTH, ROTATION OF THE PLANETS, A CATALOGUE OF FIXED STARS.