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# Saros Cycle

Sun 9 Nov, 2014 04:13 am
I've been doing some research about it but still I don't know how it works.
Could someone explain me how Saros Cycle works? I don't know where all those "120", "180", etc come from.
I know it is a calendar of (solar/lunar) eclipses and that it starts with one eclipse year "a" and it finishes year "b" but are there any calculations/general formula behind it?
Thanks.
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Ragman

1
Sun 9 Nov, 2014 08:16 am
@esther MS,
If you have been doing research, do you use Wikipedia or Google? If you have, then you would have seen this:
http://en.wikipedia.org/wiki/Saros_(astronomy)
esther MS

1
Sun 9 Nov, 2014 12:33 pm
@Ragman,
Yes, I have, both Spanish and English versions (I'm Spanish) but I still don't understand why it is divided in those numbers .
The thing is that I have (kind of) developed a function to predict lunar and solar eclipses and when I compare my results with wikipedia's they coincide but I have no division in "120" cycle or "180". I just can see when it occurs but not this subtype or whatever it is.
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rosborne979

1
Sun 9 Nov, 2014 03:01 pm
@esther MS,
esther MS wrote:
I don't know where all those "120", "180", etc come from.

Where are you seeing those "120's" and "180's"? Is there a particular link you are working from?
esther MS

1
Sun 9 Nov, 2014 04:25 pm
@rosborne979,
http://en.wikipedia.org/wiki/Solar_Saros_136
This one for example, Saros 136
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Ragman

1
Sun 9 Nov, 2014 04:30 pm
@esther MS,
esther MS wrote:

Could someone explain me how Saros Cycle works? I don't know where all those "120", "180", etc come from.

If you bothered to read the Wiki article, it states about the number 120:

"The saros is not an integer number of days, but contains the fraction of ⅓ of a day. Thus each successive eclipse in a saros series occurs about 8 hours later in the day. In the case of an eclipse of the Sun, this means that the region of visibility will shift westward about 120°, or about one third of the way around the globe, and the two eclipses will thus not be visible from the same place on Earth. In the case of an eclipse of the Moon, the next eclipse might still be visible from the same location as long as the Moon is above the horizon. Given three saros eclipse intervals, the local time of day of an eclipse will be nearly the same. This three saros interval (19,755.96 days) is known as a triple saros or exeligmos (Greek: "turn of the wheel") cycle."

The 180 number is half of 360...the degrees in a complete circle.
esther MS

1
Mon 10 Nov, 2014 10:37 am
@Ragman,
Thanks
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