Eclipse Trivia - The Saros

Updated: 4 September 2007

One of the most well known eclipse periods is the Saros. After 18 year and 10 or 11 days and 8 hours, an eclipse repeats. E.g. after the total eclipse of 11 August 1999 the next one in this series will be 21 August 2017. As the eclipse happens 8 hours later on the day, it will take place approximately 120° to the West. So the 2017 total eclipse will be visible from the United States of America.

A new Saros series starts as a small, or often tiny, partial eclipse. The Saros series 140 started on 16 April 1512 with a tiny eclipse of magnitude 0.0003, whereas Saros series 152 started on 26 July 1805 with a small eclipse of magnitude 0.1407
 

 
The graph belows shows the types of eclipse during a Saros series. The first eclipse of a Saros is no. 1 on the bottom. The Saros series displayed here start and end with minimum 6 up to 24 partial eclipses (average 13). In between there are annular, hybrid and total eclipses. A hybrid is also called annular-total. Some Saros series have no total or hybrid eclipses. For Saros series 31 to 58 and 86 to 116 this is the case for every third series. A remarkable Saros in this respect is 43, that started with 8 partials, followed by 55 annular eclipses and ended with 9 partials. Some (69, 72, 75, 127 and 130) have no annular nor hybrid eclipses.

If we use a letter for a series of eclipse, e.g. PAP stands for series of partials, followed by series of annulars, followed by series of partials, the following sequences do occur: PAP, PTP, PAHTP, PTHAP, PHTP and PTHP. Sequences PHP, PATP, PTAP, PHAP, PAHP, and sequences with 2 A's or 2 H's do not occur in the sample considered.


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