A History of Astronomy

according accurate afterwards already ancient appeared assumed astronomical attraction basis became bodies bright calendar called cause celestial centre century circle comet complete computed consisted constructed continued course derived described determined developed difficult direction discoveries distance earth eclipses entirely epicycle equal error exact exactly explained expressed fixed followed force gave give given gravity greater Greek hence ideas important increasing indicated Italy Jupiter king knowledge known larger later latitude less light lines longitude lunar magnitude Mars matter means measured mentioned method month moon motion moving names nature needed object observations Observatory opposition orbit parallax period phenomena planetary planets position practical problem progress Ptolemy published regular relative remained rise rotation Saturn seen showed smaller solar space sphere stars tables telescope theory tion universe Venus visible