Saros History

The total eclipse of 1995 October 24 is the twenty-second member of Saros series 143, as defined by van den Bergh [1955]. All eclipses in the series occur at the Moon's ascending node and gamma[7] decreases with each member in the series. The family began on 1617 Mar 2 with a partial eclipse at high latitudes in the northern hemisphere. During the first one and a half centuries, ten partial eclipses occurred with the eclipse magnitude of each succeeding event gradually increasing. Finally, the first umbral eclipse occurred on 1797 Jun 24. The event was a total eclipse visible from the Arctic Ocean and eastern Siberia. Perhaps the most remarkable characteristic of this eclipse was its unusual umbral path nearly 1000 kilometers wide. During the 1800's, the series continued producing total eclipses whose maximum durations gradually increasing to nearly four minutes.

Some of the eclipses of Saros 143 have contributed significantly to our understanding of the Sun. For instance, during the total eclipse of 1851 July 28, Airy described the Sun's chromosphere in detail, while Grant, Swan and von Littrow determined that prominences were a physical part of the Sun, rather than the Moon. The first photograph of the corona, a daguerreotype, was made in Prussia at this event. The following eclipse of 1869 Aug 7 passed centrally through the United States and is notable for the major scientific expeditions organized to study it. Young and Harkness independently discovered a mysterious, bright green line in the corona's spectrum. It wasn't until 1941 that Edlén identified the line as iron that has lost 13 electrons (Fe XIV). In Russia, Mendeleev used a balloon to ascend above the clouds to observe the total eclipse of 1887 Aug 19. One saros period later, the umbra's path crossed through Spain during the well observed eclipse of 1905 Aug 30.

Although each succeeding path was shifting south towards the equator, the duration of totality began dropping. This was due to the Moon's progressively increasing distance from Earth as each eclipse occurred nearer to apogee. By 1977 Oct 12, the duration had dropped below three minutes. The 1995 Oct 24 event is the twelfth and last total eclipse of Saros 143. The next event of 2013 Nov 3 is a hybrid eclipse since it is total along most of its path but becomes annular near the sunrise and sunset portions of the track. The following three events are each annular/total as the path of totality grows progressively narrower and shorter. Finally, the series produces its first entirely annular eclipse on 2085 Dec 16.

During the next two and a half centuries, the duration of annularity gradually increases as the paths regress northward. The trend north is due to the passage of Earth through the vernal equinox which shifts the northern hemisphere southward with respect to the geocenter. The paths resume their southern migration with the eclipse of 2338 May 20. The duration of annularity now exceeds two minutes. The remaining eleven annular members of the series possess paths that shift progressively south while the duration gradually rises above four minutes. The final annular eclipse occurs on 2536 Sep 16 with a duration of 4 minutes 48 seconds. As the series winds down, it produces twenty more partial eclipses at high southern latitudes. Saros 143 finally ends with its seventy-second event on 2897 Apr 23.

In summary, Saros series 143 includes 72 eclipses with the following distribution:

Saros 143	Partial	Annular	Ann/Total     Total     
-----------     ------- ------- ---------     -----
Non-Central	  30	   0	    0		 0         
Central		  --	  26	    4		12

[7] Gamma is measured in Earth radii and is the minimum distance of the Moon's shadow axis from Earth's center during an eclipse. This occurs at and defines the instant of greatest eclipse. Gamma takes on negative values when the shadow axis is south of the Earth's center.
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