- A. T. Grafton
ExtractSolar and lunar eclipses rank with the most impressive celestial phenomena. They were widely considered ominous—as the story of *Nicias (1)'s final defeat in Sicily shows—and some 250 reports of them occur in ancient sources. The Babylonian records of lunar eclipses to which *Ptolemy (4) had access apparently began in the 8th cent. bce. By the 5th cent., well-informed Greeks like *Thucydides (2) understood (2.28) that solar eclipses can take place only at new, and lunar ones at full moon. *Hipparchus (3), in the 2nd cent., supposedly predicted the motions of the sun and moon, including their syzygies, for 600 years; and Ptolemy, 300 years later, provided precise methods for predicting the time not only of lunar, but also of solar eclipses (a much harder task). Recorded eclipses in Greek and Roman literature provide the only absolute dates for historical phenomena (like the *Peloponnesian War): the dated eclipses recorded by historians of the later Roman republic make it possible to trace the deviation of the months of the republican calendar from their proper positions.
- Science, Technology, and Medicine