The Time to Recite Keriat Shema and Ma'ariv

5.The Time to Recite Keriat Shema Begins at Tzeit HaKochavim
The time to recite the evening Keriat Shema is "when you lie down" – when people lie on their beds to sleep, which starts when it gets dark. The Chachamim established a sign for the beginning of this time, when three medium-sized stars can be seen in the sky. This is because large stars are also visible during the day or at bein hashemashot (twilight). However, when three medium-size stars (according to the naked eye) emerge after them, it is a sign that night has begun (HaZemanim BaHalachah chapters 49-50). This time is called tzeit hakochavim. To avoid error, and to prevent mistaking big stars for medium ones, the Rishonim write that one must wait until he sees three small stars appear in the sky (Talmidei Rabbeinu Yonah; Shulchan Aruch 235:1).
However, here an uncertainty arises: how do we establish the time of tzeit hakochavim? Some say that the time of tzeit hakochavim is established according to those with good eyesight, and who know where the first stars are located. They can see the three medium stars approximately eighteen minutes after sunset, and sometimes even fifteen minutes after sunset. This is also implied from the Talmud (Shabbat 35b), which states that the time between sunset and tzeit hakochavim is the walking distance of three-quarters of a mil, which is approximately between thirteen-and-a-half minutes to eighteen minutes. Others say that it is established according to the majority of people, for most people discern three medium stars approximately 25 to 30 minutes after sunset. All this is said in reference to medium stars. However, as mentioned previously, the Rishonim write to wait until three small stars are visible; therefore, it is necessary to wait another few minutes.
In practice, many are accustomed to start praying Ma’ariv approximately 20 minutes after sunset, for that is the halachah according to the majority of poskim. L'chatchilah, it is best to start Ma’ariv approximately 30 minutes after sunset. One who prays in a minyan in which Keriat Shema was recited before 30 minutes passed from sunset, should go back and repeat the first paragraph of Shema after Aleinu L’Shabe’ach in order to avoid uncertainty. Those who wish to be stringent say V’Hayah Im Shamo’a as well. There are those who also add Vayomer. 3

6.The Time of the Amidah According to the Chachamim and Rabbi Yehudah
The time of the Ma’ariv prayer was established to correspond to the offering of the organs and fats of the Tamid offering upon the altar. As we already learned (earlier in this book 24:7), the Chachamim and Rabbi Yehudah disagree regarding this matter. According to the Chachamim, the time of Minchah is until night, and the time to pray Ma’ariv starts from tzeit hakochavim. According to Rabbi Yehudah, the time of Minchah ends at plag haminchah, an hour and a quarter before the end of the day, and immediately after that begins the time of Ma’ariv. A person is permitted to choose whether to practice according to the Chachamim or Rabbi Yehudah, on condition that he adheres to one minhag. If he follows Rabbi Yehudah, he must make sure not to pray Minchah after plag haminchah. If he follows the Chachamim, he must make sure to pray Ma’ariv after tzeit hakochavim. However, if a person prays Minchah after plag haminchah in the opinion of the Chachamim, it is forbidden to pray Ma’ariv before tzeit hakochavim according to Rabbi Yehudah.
Even though according to Rabbi Yehudah the time to recite Ma’ariv and Birkot Keriat Shema starts at plag haminchah, the time of Keriat Shema itself does not begin until tzeit hakochavim. Therefore, a person praying before tzeit hakochavim must repeat the three paragraphs of Shema after tzeit hakochavim (Shulchan Aruch 235:1). 4
L'chatchilah, one may not switch from one ruling to another; instead, everyone must always practice according to one opinion. The prevalent minhag today is to follow the Chachamim. However, in times of need, a person is permitted to change from the Chachamim’s opinion and practice like Rabbi Yehudah. For instance, in the summer, when Shabbat starts late, there are those who wish to accept Shabbat early so that their small children can participate in the prayer service and the meal, and for that reason they pray Ma’ariv like Rabbi Yehudah, before sunset. Similarly, a person who finds himself in a place in which they practice like Rabbi Yehudah, even though he is used to praying Ma’ariv after tzeit hakochavim, it is better that he pray in a minyan like Rabbi Yehudah, instead of observing his minhag and praying individually like the Chachamim. 5

7.The B’dieved Custom Linking Minchah to Ma’ariv Before Its Proper Time
In some congregations, it was customary to pray Minchah and Ma’ariv, one right after the other, between plag haminchah and tzeit hakochavim. During the time of the Rishonim, this custom was practiced primarily in Ashkenaz, and in the time of the Acharonim, mainly in Spain. Many prominent rabbis questioned this minhag and attempted to abolish it, for it is a custom which contradicts itself; since they prayed Minchah after plag haminchah like the opinion of the Chachamim, it is impossible to pray Ma’ariv at that time like Rabbi Yehudah. Hence, it is proper to arrange Torah learning between Minchah and Ma’ariv, and in that way, the people praying will merit to learn Torah and to fulfill the Ma’ariv prayer in its proper time.
Nonetheless, the Acharonim instruct that if waiting until after tzeit hakochavim will cause the people to disperse and the Ma’ariv prayer to be cancelled, it is possible to be lenient and recite Ma’ariv immediately after Minchah. Of course, all those praying must repeat Keriat Shema after tzeit hakochavim. 6
Concerning an individual who normally prays according to the Chachamim’s approach, namely, Ma’ariv after tzeit hakochavim, and finds himself in a place in which they observe the minhag of extenuating circumstances – Minchah and Ma’ariv one right after the other before tzeit hakochavim – there is disagreement. Some say that it is preferable that the individual prays with them, so that he prays in a minyan. Others say that it is better that he preserves his minhag, prays Minchah with them in the minyan, but prays Ma’ariv individually after tzeit hakochavim. 7

^ 3.See HaZemanim BaHalachah chapters 47-51. See also Peninei Halachah Shabbat I, p. 52 and in the footnotes. In Shabbat 35 the time of bein hashemashot (twilight) is explained according to Rabbi Yehudah to be the amount of time it takes to walk three-quarters of a mil, and according to Rabbi Yossi, to be a short amount of time (approximately half a minute). The majority of poskim maintain that Rabbi Yossi’s bein hashemashot is immediately after the time of Rabbi Yehudah’s bein hashemashot. The halachah sides with both of them, meaning that from sunset until a little more than the time it takes to walk three-quarters of a mil is the time of bein hashemashot. (Some maintain that the bein hashemashot of Rabbi Yossi is a few minutes after the bein hashemashot of Rabbi Yehudah, as brought by HaZemanim BaHalachah 40:8-11, and then the time of Ma’ariv is later by a few more minutes.) As we learned earlier in chapter 11, note 1, there are three opinions regarding the amount of time a mil represents: 1) 18 minutes, 2) 22.5 minutes, and 3) 24 minutes. Based on this, three-quarters of a mil is between 13.5 minutes and 18 minutes. In order to incorporate the time of Rabbi Yossi, a little more time must be supplemented, and the result according to this, is that the final time of bein hashemashot is between 14 and 19 minutes.
However, there are differences between the seasons of the year, for in Nisan (March 5 th) and Tishrei (October 5 th), the light fades faster after sunset and therefore it is possible to see three stars earlier. For instance, what can be seen in Nisan, 19 minutes after sunset, is visible at the peak of summer (June 22nd) almost 22 minutes after sunset, and at the height of winter, 21 minutes after sunset.
It is also important to understand that one who stands high above sea level sees the sunset later. For example, one who stands on a mountain, or in a tower at a height of approximately 800 meters above sea level, will see the sunset about five minutes after his friend who stands at sea level below. In other words, the sky will darken at the same time for both of them and they will see the stars simultaneously, but if each of them were to calculate the amount of time that passed from sunset to tzeit hakochavim, there would be a difference of approximately five minutes. Those who are higher see the sun for five more minutes. Based on this, if the Chachamim were talking about Jerusalem, whose height is approximately 800 meters above sea level (at places where the mountains do not block the horizon), in regard to this calculation, 14 or 19 minutes in Jerusalem is like 19 or 24 minutes at sea level. A few laws can be clarified after understanding this point.
In Israel, on a straight horizon at sea level during the days of Nisan (March 5 th) and Tishrei (October 5 th), 14 minutes after sunset, the sun descends only 3.75 degrees below the horizon. This approach poses difficulty, for at that time, few, save the most skilled, rarely succeed in seeing three stars. See HaZemanim BaHalachah 41:7 for explanations given by the Acharonim. Some say that perhaps the halachah is based on people with better vision, and others argue that maybe people living at that time had superior eyesight. As aforementioned, it is possible to conclude that the Chachamim were talking about Jerusalem, at a place where the hills do not block the horizon, and then the sunset is five minutes later, and it turns out that 14 minutes after sunset in Jerusalem is like 19 minutes after sunset in the Shefelah (the lowlands region of Israel).
Indeed, according to those who maintain that tzeit hakochavim is 19 minutes after sunset in the Shefelah, the sun descends at that time 4.8 degrees below the horizon, and then experts who know where the first stars should be seen in the sky can see three medium-sized stars in the days of Nisan. However, in the summer days, one must wait 22 minutes for that same situation to arise, and in the winter, 21 minutes.
Some say that three medium stars are actually only visible when the sun descends approximately 6.2 degrees below the horizon, which is 25.5 minutes after sunset during Nisan, 28 minutes at the height of winter (December 22 nd), and 29.5 minutes at the height of summer (June 22 nd). At that time, most people see three medium-sized stars. Perhaps it somewhat resembles the opinion which maintains that tzeit hakochavim is 19 minutes after sunset in Jerusalem, and at sea level it comes out to approximately 24 minutes after sunset (maybe another minute and a half were added since today eyesight has weakened, or because the abundance of electric lights make it more difficult to see the stars, although perhaps it is truly possible to see the stars slightly before that).
There are those who are more stringent and maintain that in actuality, most people do not see three stars before the sun descends 7.1 degrees below the horizon, which is around 30 minutes after sunset during Nisan and Tishrei at sea level, and in the summer, approximately 35 minutes. This is what has been said in the name of the Chazon Ish. However, it is difficult to explain the words of these stringent poskim according to the Gemara who allotted that the time it takes to walk three-quarters of a mil to bein hashemashot. Additionally, concerning calculations made in open areas in which there are no lights and electricity, people saw three stars before then. See HaZemanim BaHalachah 47:12; 50:6-7. The additional aspects of this issue require further examination. For example, in Tishrei, even though the duration of the darkening of the skies is similar to Nisan, we see the stars slightly later due to the position of the stars in the skies; and the question is, do we go by the stars or according to the darkness? See Hazemanim BaHalachah, chapter 48.
All the aforementioned refers to the time of three medium stars. However, so that people will not come to err, the Shulchan Aruch rules that they must wait until three small stars emerge, meaning, another few minutes. Some say that nowadays, since we use clocks, there is no need to wait. See HaZemanim BaHalachah 51, note 3. Nevertheless, even according to those who are stringent l'chatchilah, if one recited Shema after three medium-sized stars emerged, b’dieved he fulfilled his obligation.
In practice, the prevalent minhag is to start Ma’ariv 20 minutes after sunset, and this is good according to the majority of poskim, as written in many halachic works. At that time, in all places, experts can see three stars, which is when the sun is at 4.8 degrees below the horizon. (Even in the Shefelah in the summer, when the congregation reaches Shema, 22 minutes will have passed.)
Although it is possible to rely on the opinion of the majority of poskim and recite Shema 20 minutes after sunset, it is better to recite Keriat Shema 30 minutes after sunset. If one recites it before then, it is best that he repeats it after praying, although it is not unnecessary to say the Vayomer paragraph. Despite the fact that according to the Sha’agat Aryeh, remembering the Exodus must also be at the proper time for Keriat Shema, nonetheless, according to the Magen Avraham, it is permissible to mention it before then, at the proper time for Ma’ariv (Mishnah Berurah 235:11). Therefore, when a person recited Shema after 18 minutes following sunset, he need not repeat Vayomer. It is not even so crucial to repeat V’Hayah Im Shamo’a since, according to the majority of poskim, the obligation to recite it is rabbinic.
L'chatchilah, so as to take into consideration those poskim who are stringent, it is good to set the time of Ma’ariv 30 minutes after sunset. That way, people living in the hills also fulfill their obligation throughout the whole year even according to the stringent opinions (the sun is 7.1 degrees below the horizon), and those in the Shefelah fulfill their obligation the whole year round, according to most opinions (6.2 degrees below the horizon), and most of the year they fulfill their obligation even according to those who are stringent. In order to always fulfill one’s obligation in the Shefelah also according to the stringent opinions, it is necessary to delay the recital of Barchu during the summer by another three minutes so that when the congregation arrives at Keriat Shema, 35 minutes will already have passed.
The law concerning the emergence of three medium-sized stars is also significant with regard to establishing the time of a circumcision for a baby born at the beginning of Shabbat. If the baby is born after tzeit hakochavim, he must be circumcised on the following Shabbat; and if he is born at bein hashemashot, it is forbidden to circumcise him on Shabbat, and his circumcision is postponed until Sunday. The matter depends on the precise time of tzeit hakochavim is. The Yabia Omer, part 7, Orach Chaim 41:8 rules that 20 minutes after sunset is certainly nighttime, and therefore the baby is circumcised on Shabbat. Shemirat Shabbat Kehilchatah, part 2, 46:45 writes in the name of Rav Auerbach that night begins definitively 25 minutes after sunset. However, the fact that neither opinion makes a distinction between Jerusalem and the Shefelah, and between the different seasons of the year is problematic. The book Otzar HaBrit 9, 5, 7, mentions that there are those who maintain that nighttime officially starts at 24 minutes after sunset, and some say 28 minutes, but that the author himself was taught that it is no less than 32 minutes after sunset. Still, he too, neglects to distinguish between Jerusalem and the Shefelah and the different seasons of the year. It seems best to follow the approach that says that night begins when the sun is 6.2 degrees below the horizon. In Jerusalem that is approximately 20.5-24.5 minutes after sunset, and in the Shefelah, 25.5-29.5 minutes after sunset. It is possible to calculate the exact time with the help of the computer program Chazon Shamayim, based on the secular date, the place of birth of the child according to the lines of longitude and latitude, and the altitude of the location.

^ 4.However, the Tosafot write in Berachot 2a that according to Rabbeinu Tam, the time to recite the evening Keriat Shema is the same as the time of Ma’ariv, and according to Rabbi Yehudah, one is permitted to fulfill his obligation from the time of plag haminchah. According to Rabbeinu Yitzchak, it is permissible in extenuating circumstances to be lenient regarding the time of Keriat Shema and to follow the opinions which say that it is a few minutes before tzeit hakochavim. Nonetheless, the remaining Rishonim maintain that the time to recite the evening Keriat Shema is after tzeit hakochavim, and therefore it is necessary to repeat Keriat Shema after tzeit hakochavim, as the Shulchan Aruch 235:1 rules. There is disagreement as to whether it is necessary to repeat the Vayomer paragraph after tzeit hakochavim as well. According to the Magen Avraham, the time to remember the Exodus from Egypt is the same as the time of Ma’ariv and one need not make it up, whereas according to the Sha’agat Aryeh its time is like the time of Keriat Shema and one must make it up (Mishnah Berurah 235:11). Regarding Birkot Keriat Shema, in principal their time is like the time of Keriat Shema. However, in practice, those who follow Rabbi Yehudah normally recite them before tzeit hakochavim and fulfill their obligation, as clarified in the Mishnah Berurah 235:7 and 11, and Sha’ar HaTzion 6.

^ 5.According to the Ra’ah and Meiri, throughout the day a person must practice according to one approach, but each day he may choose a different minhag. According to Talmidei Rabbeinu Yonah, Rashba, and the Rosh, one must always choose to follow one opinion and he is not allowed to switch approaches even from time to time. The Shulchan Aruch 233:1, Mishnah Berurah 6:11 and Kaf HaChaim 9:12 rule that, l'chatchilah, alternating approaches is prohibited, but in times of need, one is permitted to do so (see Mishnah Berurah 267:3).
^ 6.The Tosafot Berachot 2a, Rosh, and Talmidei Rabbeinu Yonah, as well as other Rishonim, question this minhag of praying Ma’ariv before sunset, for it involves two lenient opinions which contradict each other. In practice, to accommodate the needs of the multitude, they ruled leniently, as written in the Mishnah Berurah 233:11, Kaf Hachaim 12, and Yalkut Yosef, part 3, 235:1. However, all agree that Keriat Shema must be recited after tzeit hakochavim. There are two main opinions concerning the proper conduct in a place where the congregation is praying Ma’ariv before tzeit hakochavim. There are two main opinions concerning how one must practice when in a place in which the congregation is praying Ma’ariv before tzeit hakochavim. According to the Rambam, he recites Birkot Keriat Shema with them and adjoins redemption to prayer, and after tzeit hakochavim he goes back and recites Keriat Shema in order to fulfill the mitzvah. That is how the Shulchan Aruch 235:1 rules. According to Rav Hai Gaon, he only recites Keriat Shema with the congregation so that from Shema he will begin the Amidah together with the minyan. However, Birkot Keriat Shema, as well as Keriat Shema itself (in which he will fulfill his obligation), are recited after tzeit hakochavim. From his opinion it appears that it is better to recite Birkot Keriat Shema with Keriat Shema, after tzeit hakochavim, even though in so doing one does not adjoin redemption to prayer. This is what the Mishnah Berurah 235:12 writes and that is how he himself practiced (see Igrot Moshe Orach Chaim 2:60). According to the Gra, it is always preferable to pray Ma’ariv individually after tzeit hakochavim like the Chachamim rather than to pray with the congregation before tzeit hakochavim like Rabbi Yehudah.
In a place in which Minchah and Ma’ariv are prayed one right after the other, it is better, if possible, to be careful to recite Minchah before sunset and Ma’ariv after sunset, for some poskim maintain that Ma’ariv time begins at sunset, and that is how the Or L’Tzion, part 2, 15:6, understands the opinion of the Shulchan Aruch. Even according to this opinion, the time of Keriat Shema is after tzeit hakochavim. Nonetheless, the majority of poskim rule that the time of the Ma’ariv prayer according to the Chachamim is, indeed, after tzeit hakochavim. That is what the Mishnah Berurah 233:9 writes.

^ 7.The first opinion is inferred from Kaf HaChaim 233:12. One makes up the three paragraphs of Shema later. The second opinion can be inferred from Sha’ar HaTzion 235:16. However, if one prayed Minchah before plag haminchah he prays Ma’ariv with the minyan and follows one of the two opinions mentioned in the previous note.