Polish astronomer Nicolaus Copernicus announced the motion of Earth in De revolutionibus orbium coelestium libri VI (“Six Books Concerning the Revolutions of the Heavenly Orbs,” 1543). (An early sketch of his heliocentric theory, the Commentariolus, had circulated in manuscript in the small astronomical community of central Europe from about 1510, but it…
Though “oracle bones” exist from the late 2nd millennium BCE that mention observations of lunar and solar eclipses as well as the appearance of a new star (nova), astronomical reports begin to be fairly numerous only from about 200 BCE. In China astronomy had an imperial function. The…
In the Latin West the level of scientific learning had sunk to a low level. None of the Greek works most important for ancient astronomy and cosmology—Aristotle’s On the Heavens and Ptolemy’s Almagest, Handy Tables, and Planetary Hypotheses—were available. The teaching of astronomy was based on…
In the 8th century, Arabic Muslim astronomers came into contact with this complicated astronomical material. Theories and methods that had passed from the Babylonians and Greeks through Persia to India now came back to the West. A good example is provided by…
Ptolemy was the last major figure in the Greek astronomical tradition. Commentaries were written on his works by Pappus of Alexandria in the 3rd century CE and by Theon of Alexandria and his daughter, Hypatia, in the 4th, but creative work was no longer being done.…
The culminating work of Greek astronomy is the Almagest of Claudius Ptolemaeus (2nd century CE). Ptolemy built on the work of his predecessors—notably Hipparchus—but his work was so successful that it made older works of planetary astronomy superfluous, and they ceased to be read and copied.…
Greek thinking about the motion of the planets began by about 400 BCE. Eudoxus of Cnidus constructed the first Greek theory of planetary motion of which any details are known. In a book, On Speeds (which is lost but was briefly discussed by Aristotle and Simplicius), Eudoxus regarded…
The breakthrough that gave Greek astronomy its own particular character was the application of geometry to cosmic problems. The oldest extant source that clearly states that Earth is a sphere and that gives a sound argument to support the claim is Aristotle’s On the Heavens (c. 350 BCE), but this knowledge…
Astronomy is present from the beginning of Greek literature. In Homer’s Iliad and Odyssey, stars and constellations are mentioned, including Orion, the Great Bear (Ursa Major), Boötes, Sirius, and the Pleiades. More-detailed astronomical knowledge is found in Hesiod’s Works and Days, from perhaps a generation later than Homer. Hesiod used the appearances and…
The earliest sophisticated astronomy arose in ancient Babylonia, in central Mesopotamia, and there are three reasons why it happened there rather than, say, in ancient Greece. First, in Babylonia astronomy had an important social function: the gods sent signs from heaven to warn the king…