Zmanim
Zmanim are specific times of the day in Jewish law.
- In Jewish law, a calendar day is defined as running from "evening" to "evening." This is based on the repetition of the phrase "... and there was evening, and there was morning..."—evening preceding morning—in the account of creation in Genesis.
- Additionally, Jewish law requires certain activities to be undertaken "during the day"—or at a certain time during the day—while other activities are to be undertaken "at night"—or at a certain time during the night.
Calculations
General approach
The Talmud often states calculations of these zmanim in terms of the time it takes to walk some distance, stated in mils. Most authorities reckon the time it takes to walk one mil as being 18 minutes, though there are opinions of up to 24 minutes. Many authorities hold such calculations to be absolute: if nightfall follows sundown by "the amount of time it takes to walk four mils," for example, that means exactly "72 minutes after sundown" in all places on all dates. Other authorities, especially those living in higher latitudes, noted that the darkness of the sky 72 minutes after sundown can vary substantially from place to place, and from date to date. They therefore hold that "72 minutes after sundown" actually refers to how dark the sky is 72 minutes after sundown in Jerusalem on an equinox. Then that degree of darkness is reckoned as being true when the sun has fallen a certain number of degrees below the horizon, and that becomes the actual standard used for all places and all dates.Evening
One calendar day ends, and the next day begins, during the evening. The Talmud states there is an uncertainty as to whether the day ends at sunset or nightfall, so the time in between has a status of doubt. The Talmud in Pesachim states there are four Biblical miles between sunset and nightfall. However, the Talmud in Tractate Shabbat states that there are three-quarters of a mil between sunset and nightfall.- The Geonim and the Vilna Gaon say that the second statement is correct.
- Rabbeinu Tam and many other Rishonim say that there are two "sunsets," the first of which, actual sunset, is four mil before nightfall, and the second of which is three-quarters of a mil before.
In practice, when the question is whether it is too late to do a something that must be done by day, the practice is to follow one of the earlier opinions. When the question is whether it is too early to do something that must be done by night, the practice is to follow one of the later opinions. For calculating the end of Shabbat or major holidays, the desire not to end Shabbat early, along with the Talmud's description of the end of Shabbat in terms of the appearance of stars in the sky, leads to the use of the later opinions.
Morning
There is also a difference of opinion as to when one may begin to do activities that must be done during the day:- Daybreak, when some light is visible, or
- Sunrise, when the ball of the sun rises [|above] the horizon.
Seasonal hours
For almost all halakhic purposes, each day is divided into twelve equal "hours." There are two major opinions:- The Magen Avraham holds that because one may do "daytime" activities between daybreak and nightfall, one calculates the day from daybreak to nightfall, and divides that period into twelve parts.
- The Vilna Gaon holds that although "daytime" activities can start as early as daybreak and end as late as nightfall, their proper time lechatchila is from sunrise to sunset, so one calculates the day from sunrise to sunset and divides that period into twelve parts.
These are called "seasonal" or "variable" hours because they depend on the length of time between sunrise and sunset, and those vary through the year. Near New York, for example, a "seasonal hour" based on the Vilna Gaon's calculations lasts around 45 minutes near winter solstice, around 60 minutes near the equinoxes, and around 75 minutes near summer solstice.
Times
Daybreak
Daybreak refers to when the first rays of light are visible in the morning.- If one has not recited the evening Shema by this time, and the omission was not due to negligence, one can still recite it now, up to sunrise, though one may not say Hashkiveinu or Baruch Hashem L'Olam.
- If one has prayed Shacharit after this time, one has fulfilled his obligation ex post facto. Furthermore, most mitzvot that must be performed during the day may be done after this time, at least ex post facto.
- One does not use tallis and tefillin before misheyakir.
Sunrise
Sof Zman Kriyat Shema
Sof Zman Kriyat Shema means "end of the time to say the Shema." This is three halachic hours into the day. These hours are variable/seasonal hours and refer to one twelfth of the time between daybreak and nightfall or one twelfth of the time between sunrise and sunset.Sof Zman Tefilah
Sof Zman Tefilah means "end of the time to say the Shacharit Amidah." This is four hours into the day. The above comments apply here also. However, since the Amidah is only rabbinically required it is common to rely on the later time, thus only a few calendars publish the earlier time.Midday
Midday means the midpoint between sunrise and sunset, or equivalently between daybreak and sundown. The absolute latest time for the Shacharit Amidah, ex post facto, is this time. On the Shabbat and on holidays, one is supposed to eat before this time. On Tish'a Ba'av one may sit on a chair at this time, and those who fast on Erev Rosh Hashanah usually eat at this time.Mincha Gedolah
Minchah Gedolah, one-half variable hour after midday, is the earliest time to recite Minchah, although one should try, if possible, to wait until Minchah Ketanah. On Yom Kippur, the congregation must begin Mussaf by this time, because otherwise they would be required to pray the more frequent prayer first.Mincha Ketanah
Minchah Ketanah, two and one-half variable hours before sunset, is the preferable earliest time to recite Minchah.Plag Hamincha
Plag Hamincha is the midpoint between Minchah Ketanah and sunset, i.e. one and one-quarter variable hours before sunset. If one prayed Minchah before this time, one may recite Maariv afterwards. Otherwise, one must wait until sunset, unless one is praying as a congregation.Sunset
Sunset is the time at which the ball of the sun falls below the horizon. The new day begins at this point for almost all purposes. For example, the calendar date changes.Mitzvot that must be performed during the day may no longer be performed ab initio. Minchah should not be delayed past now. Maariv may be recited now, although many wait until after nightfall.
Sunset's calendar date change effects include knowing how to match secular date of passing away with Yartzeit date.
Bein Hashemashot
Bein Hashemashot is the period between sunset and nightfall, and is considered a time of questionable status. On the Sabbath, festivals, and fast days the stringencies of both the previous and following days apply. For example, if the fast of Tish'a Ba'av immediately follows the Sabbath, the intervening Bein Hashemashot is forbidden in eating, drinking, and working. However, there are occasional leniencies.Nightfall
Nightfall is described in detail above. After nightfall, it is considered definitely the following day. All restrictions of the previous day go away, and any Mitzvot that must be performed at night (such as the evening Shema, the Seder, or Bedikas Chametz may be performed.[|End of Shabbat]
מוצאי שבת, the End of Shabbat, is described in the Talmud as a time when "three medium stars are in the sky." There is much discussion of what this means, and not to end Shabbat "too" early, it tends to be construed strictly in practice. There are various observed practices, all of which have support in the halachic literature:- Appearance of three medium-sized stars in the sky.
- Appearance of three small stars.
- 72 minutes after sundown. Common practice in Chasidic and other Charedi communities.
Midnight
Other zmanim
On the Eve of Passover, chametz may not be eaten after four variable hours, and must be burned before five variable hours.The Mussaf prayer should preferably be recited before seven variable hours, on days it is recited.