Yom Kippur in 2010 is on Saturday, the 18th of September.
Note that in the Jewish calander, a holiday begins on the sunset of the previous day, so observing Jews will celebrate Yom Kippur on the sunset of Friday, the 17th of September.
> “Note that in the Jewish calander, a holiday begins on the sunset of the previous day”
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Except that Yom Teruah technically begins when the first crack of light of the new moon shows (in Jerusalem).
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