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Times are a Changing...


As you know, this past Sunday we switched from Daylight Savings Time to Standard Time. What you might not realize is that the time change impacts our Shabbat morning schedule. Until this week, we were able to begin services at 9:30 a.m. However, for the next month we must begin at 9:15 a.m.

Allow me to explain. When the daily morning service was instituted (just a few thousand years ago), it came with a sunup-based timeline. This means that the morning Shema and Amidah need to be completed within several “halachic hours” from sunup. A halachic hour is determined by dividing the total amount of daylight by twelve. Therefore, in the winter a halachic hour could be as short as 48 minutes and, in the summer, it could be as long as 74 minutes.

For example, sunup this coming Shabbat is at 6:47:06 a.m. and sundown is at 5:00:42 p.m., which means there will be 10 hours,13 minutes and 36 seconds of daylight. By converting that into minutes (10x60+13=613 minutes and 36 seconds) and then dividing by 12 you get a 0:51.07- halachic hour. According to this calculation, the Shema (which needs to be recited before the end of the third halachic hour of the day) should be finished by 9:20 a.m. The Amidah (which needs to be said by the end of the fourth halachic hour) should be finished by 10:11 a.m.

Optimally, a synagogues’ service times should be in sync with the halachic hour system and allow for the Amidah to be recited right after the Shema. Here in San Francisco, that would require starting Shacharit on Shabbat at 8:30 a.m. However, there is a long-standing custom in many shuls for people to recite the Shema (in its proper time framework) independently before the beginning of the service. Though this custom is not optimal - it works. Adath Israel has historically followed this custom, and therefore, in order to at least recite the Amidah within its proper time framework, the Shabbat morning service will begin at 9:15 a.m.