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Reference of Measurements in Halacha: Difference between revisions
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* There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons. | * There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons. | ||
* A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset. | * A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset. | ||
* Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that Meshiyakir is between 50 and 60 minutes before sunrise in Jerusalem - In New York, depending on the time of the year, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.</ref> | * Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that Meshiyakir is between 50 and 60 minutes before sunrise in Jerusalem - In New York, depending on the time of the year, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted. | ||
* [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that MeSheYakir is about 40 or 50 minutes before sunrise.</ref> | |||
==Olot HaShachar== | ==Olot HaShachar== | ||
# Many rishonim hold that Olot HaShachar is 72 minutes before sunrise on a perfect day in Jerusalem which is equivalent to when the sun is 16 degrees below the horizon for everywhere in the world, however, others hold that Olot HaShachar is 90 minutes on a perfect day which is 19.78 degrees below the horizon. <ref>Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Biur Halacha 163:1 D"H Berachok). However, he totally rejects the opinion that Olot HaShachar is 120 minutes before sunrise. He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes. </ref> | # Many rishonim hold that Olot HaShachar is 72 minutes before sunrise on a perfect day in Jerusalem which is equivalent to when the sun is 16 degrees below the horizon for everywhere in the world, however, others hold that Olot HaShachar is 90 minutes on a perfect day which is 19.78 degrees below the horizon. <ref> | ||
* Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Biur Halacha 163:1 D"H Berachok). However, he totally rejects the opinion that Olot HaShachar is 120 minutes before sunrise. | |||
* He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes. | |||
* [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentions in passing that Olot HaShachar is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref> | |||
==Shaot Zmaniot== | ==Shaot Zmaniot== | ||
# Shaot Zmaniot are halachic hours which are calculated by dividing the daytime hours into 12. There’s a dispute of how to measure the day; some count the day from Olot Shachar until Tzet HaKochavim (Magan Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri Chadash 443, Magan Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magan Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>and some count it from Netz until Shekiah (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from Netz incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagot Maimon, and Mordechai (Pri Chadash rejects his proofs), Shiltei Hagiborim on the Mordechai (Brachot 4:3) (as understood by Magan Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot Yom Tov (Pesachim 2:3), and Biur HaGra 459:2.</ref> | # Shaot Zmaniot are halachic hours which are calculated by dividing the daytime hours into 12. There’s a dispute of how to measure the day; some count the day from Olot Shachar until Tzet HaKochavim (Magan Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri Chadash 443, Magan Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magan Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>and some count it from Netz until Shekiah (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from Netz incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagot Maimon, and Mordechai (Pri Chadash rejects his proofs), Shiltei Hagiborim on the Mordechai (Brachot 4:3) (as understood by Magan Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot Yom Tov (Pesachim 2:3), and Biur HaGra 459:2.</ref> | ||
