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Is it possible to calculate the candle lighting time based on location and date alone?

Assume all you have is a GPS, a watch and a calculator.

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Mordechai Ben Daniel, Welcome to mi.yodeya, and thanks very much for the interesting question! I look forward to seeing you around. – Isaac Moses Dec 1 '10 at 20:08
Keep in mind that one is not allowed to start Shabos at a later time than the community's latest starting time. So if you "prove" that candle lighting should be 3 minutes later than the time that the community lights, you still can not start Shabos later than when the community does if you proof is not accepted. But if you are on the road or stuck in an airport outside of a city, start calculating - You may even want to use Rabeinu Tam time :-) – inSeattle Dec 6 '10 at 4:03
Also can Be done With – SimchasTorah Dec 6 '10 at 4:04
Although that's going to be at the end of kabbolas shabbos/borchu which is usually after that time. – YDK Dec 6 '10 at 7:44

1 Answer 1

up vote 9 down vote accepted

Theoretically yes (assuming candle lighting is just 18 minutes less than sunset), as here's the formula for sunset time based on date, latitude, and longitude; but it's a doozy!

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Interesting that no one adjusts the 18 minutes. – YDK Dec 1 '10 at 21:43
what about altitude? – Sam Dec 2 '10 at 2:14
@YDK - adjust it for what? IIUC, the 18 minutes are a sort of buffer zone to ensure that Shabbos won't be violated. That doesn't change depending on where a person is located. – Dave Dec 2 '10 at 3:47
@Sam - Unless you're way above sea level, like in an airplane, altitude won't have a significant effect on the time of sunset. A more complicated question is how to deal with mountainous terrain; see this link for a comprehensive discussion about it: – Dave Dec 2 '10 at 4:25
@Dave, we treat the 18 as buffer zone, but those into chumra-of-the-month club would point to the Yereim, who holds halachic sunset is 18 minutes before what we call sunset. Was his opinion 18 absolute minutes or relative minutes? I don't know the material well enough (but it's based on the whole discussion of how many miles the average person walks between sunrise, sunset, dusk, etc.) – Shalom Dec 2 '10 at 14:15

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