Saros Cycle

The Saros Cycle is a period of 223 lunar months that are used to predict the eclipses of the Sun and Moon.
Saros in Greek meant ‘to Repeat’.

The Eclipse times could be calculated and predicted by the Babylonians and the Ancient Egyptians.
They knew that groups of Eclipses reoccur in a cycle that repeats itself just over every 18 years and known as the Saros Cycle.
Once the time of a previous eclipse is logged, it becomes possible to calculate the next group of eclipses.

Synodic Month:
- 29 Days, 12 Hours, 44 Minutes, 2.8 seconds.
- This is the time taken from one Full Moon to the next.
Draconic Year:
- 346 Days, 14 Hours, 52 minutes, 54 seconds.
- This is the Time taken for the Sun to move from on Lunar Node to the next, (Lunar Node is the point where the Moon’s Orbit intersects the Sun’s Orbit (Ecliptic). It is a few weeks shorter than the calendar year.
Anomalistic Month:
- 27 Days, 13 Hours, 18 Minutes, 33.2 seconds.
- The time taken for the Moon to complete its Elliptical orbit around the Earth, from Perigee when it is nearest to Earth, to Apogee when it is farthest from Earth, and back to Perigee.

The Three Cycles repeat after 18 years, 11 days, 8 hours and a few minutes.
- Synodic Month x 223 = 18 years, 11 Days (6585 Days), 7 hours, 43 minutes
- Draconic Year x 19 = 18 years, 11 days (6585 Days), 18 hours, 44 minutes
- Anomalistic Month x 239 = 18 years, 11 days (6585 Days), 12 hours, 53 minutes

To Predict the next Eclipse, the Time of observation of the last Eclipse was recorded, 18 years, 11 Days and 8 hours was then added, and the result was the Date of the new Eclipse.

The slight difference in hours will eventually add up, and after 70 to 80 Saros Cycles, the Saros cycle comes to an end. A Saros Cycle Family can last from 1200 to 1400 years.
Whilst the family of Saros cycles is in decline, a new Saros cycle begins and can overlap. So it is possible to have different families of Saros Cycles occurring at the same time.
At any given moment there are 80 Saros cycles occurring simultaneously: 38-42 Solar Saros cycles, and 38-42 Lunar Saros cycles, all in different phases of development.
The total Saros cycle pattern is complex.
The Babylonians studied Eclipses not as individual Events in a Saros Cycle, but as Events as part of a known Saros Family. The Saros cycle and the Saros Familiy were named or numbered.