Many observances in Jewish law are performed at specific times during the day. The calculation of these halachic times, known as zmanim (Hebrew for “times”), depends on the various astronomical phenomena of the day for the specific locale. Sunrise, sunset, the amount of time between them, and the sun’s angular position before rising are all factors that determine the halachic times and “hours” of the day.
[The hour has special meaning in Jewish law. When we say that a certain mitzvah may be performed three hours into the day, this doesn’t mean at three in the morning, or three clock hours after sunrise. Rather, an hour in halachah means 1/12th of the day. Thus, if the sun rises at 5 AM and sets at 7:30 PM, one shaah zmanit, or proportional hour (pl. shaot zmaniot), will be 72.5 minutes, and all calculations will use that number.]
Below you will find the times, their meanings, and some of their associated mitzvot.
Halachic dawn. Fasts begin at this time. According to Torah law, dawn marks the beginning of the day, and all mitzvot associated with daytime hours—such as hearing the shofar, taking the Four Species, the recitation of the Shema, or hearing the Megillah—can now be done. For various reasons, however, the sages instituted that the observance of many of these mitzvot should be delayed until hanetz hachamah, others until the moment “when one can recognize a familiar acquaintance.”
Earliest time for Tallit and Tefillin:
The halachic description of this time is “when one can recognize a familiar acquaintance” from a distance of approximately six feet. This is also the earliest time one can say the morning Shema.
Sunrise. Those who wish to pray kevatikin start the recitation of the Amidah at this time.
Three shaot zmaniot into the day. Latest time of the day to fulfill the biblical requirement to recite the morning Shema. Bedi’eved (if one missed this time), one should still recite Shema with its blessings until chatzot.
Four shaot zmaniot into the day—ideally the latest time for Shacharit, the morning prayer. However, if this time was missed, Shacharit may be recited until chatzot.
Midday; the halfway point between sunrise and sunset. Half-day fasts end at this time.
Half a shaah zmanit after chatzot. This is the earliest time one may recite Minchah, the afternoon prayer.
Nine and a half shaot zmaniot into the day. According to certain halachic authorities, it is preferable to wait until this time before praying Minchah.
One and a quarter shaot zmaniot before sunset. According to Rabbi Judah, this is when halachic nighttime begins. Therefore, if one chooses to follow his opinion, one recites Minchah before plag haminchah, and then Maariv (the evening prayer) may be recited anytime after plag. This is also the earliest one may bring in the Shabbat on Friday afternoon.
The accepted custom is to light Shabbat and Yom Tov candles 18 minutes before shkiah (sunset). Some communities have adopted earlier times as their unique custom for candle-lighting time.
Sunset. The latest time for Minchah (the afternoon prayer) and all mitzvot associated with the daytime hours. Bedi’eved (if one missed this time), one may still recite Minchah, and do all “daytime mitzvot,” until tzeit hakochavim (although the blessing on the mitzvah would be omitted if done after shkiah).
The Jewish 24-hour day begins at nightfall. However, the technical definition of nightfall is unclear. It can be as early as shkiah or as late as tzeit hakochavim, Therefore, the time following shkiah and before tzeit hakochavim is called bein hashmashot. Many laws relate to this period, and it can be categorized as either the previous or the next day.
The time when three average stars are visible in the sky and nightfall is complete. Earliest time for Maariv (the evening prayer) according to Rabbi Judah’s rabbinic counterparts. Earliest time for reciting the evening Shema and for counting the Omer. A woman who has completed her cycle of seven pure days goes to the mikvah after this time. This is also the time when fast days, Shabbat, and holidays may be concluded.
Proportional hour—i.e., an hour according to halachah. Total daylight hours divided by 12.