Predicting Eclipses

A solar eclipse occurs when the Moon passes between Earth and Sun. This alignment repeats in the Saros cycle of about 18 years, 11 days. Ancient Babylonian astronomers discovered this pattern and could predict eclipses without any understanding of gravity or orbital mechanics.

The geometry is precise: the Moon is about 400 times smaller than the Sun but also about 400 times closer. This cosmic coincidence means they appear nearly the same size in our sky, producing the spectacular total eclipses unique to Earth among known planets.