Eclipses & the Saros cycle
Babylonian in origin; named 'Saros' by Edmond Halley (1691)
Babylonian astronomers recognised that eclipses recur in a cycle of about 18 years and 11 days, and Edmond Halley applied the old word 'Saros' to it in a 1691 paper. Eclipses have been read as omens of consequence since antiquity, and modern astrology inherits both the prediction and the interpretation.
What it measures
The exact times of the next solar and lunar eclipses, from a real eclipse search, with their type (total, annular, partial, penumbral). An eclipse is a New or Full Moon that falls close enough to the lunar nodes for the shadow to line up.
Sources
- Edmond Halley, Philosophical Transactions (naming the Saros) (1691)