Birkat Hachama is a special blessing made on the “anniversary” of the sun’s apparent motion from the earth. It is a rare and special blessing in that it is made only once every 28 years and one normally only has two or so chances in a lifetime to perform. Birkat Hachama will be said this year on April 8th 2009, and as that date gets closer and closer you’ll find more and more people discussing this fascinating topic.
The following is condensed version of Rabbi Bleich’s sefer on Bircas haChammah. I found the entire subject matter extremely fascinating and I decided to include all the background about the calendar, the sun, and the early Jewish formulation – but in truth, one can skip to the Section 4: Birkat Hachamma and understand all the pertinent information.






There are 2 different ways of recording time and thus making a calendar. The first is based on the sun, where the earth completes a full cycle around the sun taking 365 days, 5 hours, 48 minutes, and 46 seconds. The second calendar system is based on the moon, where the each month the moon rotates around the earth taking 29 days, 12 hours, 44 minutes and 2.841 seconds.
The problem is that these two systems don’t reconcile well together. The total of 12 lunar months is still about 11 days short of one solar year. In just a few years the difference would become extremely noticeable and while we are used to having January in the cold of the winter, over time it would migrate to the summer season. Since the torah requires that the holiday of Passover occurs in the spring – it is therefore necessary to come up with some sort of “lunisolar” calendar which reconciles the two systems.
Therefore the system that we use now, adds an extra month every few years to adjust the months with the seasons. Hillel realized that in 19 solar years, you could find, to an extremely accurate degree, 235 lunar months.
19 times 12 is 228, and the remainder of 235 – 228 is 7. Therefore, if we were to put 12 lunar months into each of those 19 solar years, there would still be an extra 7 lunar months left over. However if 7 of the 19 years had 13 months while the remaining 12 years had the normal 12 months then everything would work out perfectly.
The truth is that there is a very very minor error to this calculation. Really, there is not exactly 235 lunar months in the same time of 19 solar years. According to Hillel’s equation, the length of the solar year is 365 days, 5 hours, 55 minutes and 25/57 seconds. But as stated above, the true astronomical length of a solar year is 365 days, 5 hours, 48 minutes, and 46 seconds! The Jewish year is about 6.66 minutes more than the astronomical year. Because the Jewish year is a tiny bit too big, it will gain an extra full day every 216 years.
Because of this extremely tiny error, over a long period of time we create extra days and therefore delay our holidays later and later. Pesach will be pushed off one full day in the true astronomical solar year every 216 years. That means we currently celebrate Pesach about 9 days later then Jews would 2000 years ago. Over a very long period of time, Pesach could potentially leave the spring season! If things were to continue as they do now, there would be a really big problem in 30,000 years!
But of course, there is no need to worry. Our current system is only meant to stand in place until the reestablishment of the Sanhedrin and Beit Din. At that time we will revert to our previous system of determining the new month based on eye witnesses. Honestly, we are not far away from such a position; it can truly come any day now. The reestablishment of a Sanhedrin can come even before the Beit Hamidkash is rebuilt, as long as the gedolim agreed to it.
The Tekufot or the seasons are completely based on the position of the earth in comparison to the sun. When the sun is at its maximum distance, on the north, from the equator  is it the summer solstice. The sun is at its maximum distance, on the south, from the equator for the winter solstice. Exactly in between these two solstices, the sun rests at the equator from the spring and fall equinox.
There are several things in Jewish Law that depend on these tekufot. For one, as we have already said, Pesach must fall in the spring season. Additionally, we begin reciting tal u’matar in the shemona esrei 60 days after Tekufat Tishrei, or the fall equinox. Most importantly, birkat hachamma is also linked to our establishment of the tekufot.
So, how are the tekufot determined? Shmuel, in Gemara Eruvin 56a, says the time from one tekufah to the next is 91 days and 7.5 hours. Accordingly, the span of one solar year should be 4 time this figure – or 365 days and 6 hours (365.25 days).
The Julian calendar that was used for over a thousand years during the Roman Empire used this exact figure. Since each year is 365 days and 1/4 of a day they would make each year 365 days and then add one full day every 4 years. However, as we already know, this figure is slightly off compared to the true astronomical solar year. The difference is that Shmuel’s year is 11 minutes and 14 seconds longer then the true astronomical year. This difference will create an extra full day every 128 years.
When the Julian calendar was first established in 46 B.C.E. the spring equinox fell on March 25th. By 1582, the equinox had backtracked all the way to March 11th! Pope Gregory XIII decreed to delete the 10 days between October 5th and October 14th in order to correct the calendar. This way, the spring equinox that was supposed to fall on March 11th now fell on March 21st.
Although that was a quick fix, the new Gregorian calendar had to come up with something to prevent future issues. Since the Julian calendar was a little longer then the true solar year, so that every 128 years it made an extra day – to fix it they would need to remove one day every 128 years. Well instead of removing one day every 128 years which would be pretty difficult to keep track of – Pope Gregory decreed that they remove 3 days every 400 years, which is certainly easier and still very very close to accurate.
The new system would still have the extra day every 4 years except for 3 times during a 400 year time block. For convenience, 3 out of 4 of the centenary years (1700, 1800, 1900) would not be a leap year even though they were due to be a leap years. Then the 4th centenary year would be a leap year (2000), and then the cycle would repeat itself every 400 years. According to this new system, the year is only 26 seconds longer then the true astronomical year and will only create an extra full day every 3326 years. That’s really really accurate!
So far, we have seen two different calculations for the determination of the solar year used in Jewish law. The first was Hillel’s length of a solar year  365 days, 5 hours, 55 minutes and 25/57 seconds. This number was based off of Rav Adda. Our second opinion was that of Shmuel’s  365.25 days.
Now, neither opinion is exact but both are relatively accurate. Rav Adda is 6.66 minutes too long while Shmuel is about 11 minutes too long. It is important to note that most rishonim explain that both Rav Adda and Shmuel knew their figures were slightly off. Rav Adda used his figure in order that it would work out that 19 solar years would accommodate 235 lunar months. It is unclear whether he knew the exact astronomical figure or not (it is certainly a possibility) but even so, we know Rav Adda purposely departed from a closer figure to a slightly more rough figure in order to make a convenient 19 year cycle to reconcile both the lunar and solar systems.
Shmuel also knew of Rav Adda’s figures and wasn’t arguing that Rav Adda was wrong. Of course Shmuel saw that Rav Adda’s figures were more precise. It was just that Shmuel wanted the system to be easy for everyone to use.
When Hillel formulated the Jewish calendar, that we still use today, he actually used both opinions. At this time in Jewish History, the temple had just been destroyed and Jews were being dispersed all over the globe. The Sanhedrin had been dismantled and was no longer able to declare the new month based on eye witnesses. There was a very real danger of having these laws being forgotten and lost as the Jews went into exile. At the time only a select few had understood these extremely complicated calculations (You’ll see throughout Shas discussions referring to Sod Ha’ibbur in very cryptic language because these complicated figures were reserved exclusively for the sages because of an incident once where Rabban Gamliel and Rav Yehoshua fought publically over when Yom Kippur was).However, now these principles had to be taught and publicized as widely as possible.
Hillel thus created a permanent calendar which would supersede the need for eye witnesses in determining the new month. Hillel’s calendar had all the months and years calculated and charted in advance for all the future generations until the Sanhedrin would be reestablished and the old system revived.
In creating this calendar, Hillel employed both Shmuel’s and Rav Adda’s figures. Rav Adda’s system is used for the purpose of intercalation (reconciling the lunar and solar system in a 19 year and 235 month cycle). Yet, Shmuel’s figure is used to determine the length of each tekufah (season) for the sake of tal u’matar and birkas hachamah.
Now, Obviously Hillel realized these two figures contradict each other – Rav Adda’s 235 months into 19 years assumes the year to be 365 days, 5 hours, 55 minutes and 25/57 seconds while Shmuel’s length of 91 days and 7.5 hours for the tekufah puts the year at an even 365.25 days. The discrepancy is 4 and a half minutes and over time could lead to some serious problems. (In case you’re interested, I’ll explain some really interesting problems that can result below)
The reason Hillel did this is because the recital of tal u’matar and birkat hahamah are primarily private. Hillel had to plan for the worst and he believed that since many people would say it to themselves, or even if jews were able to create a minyan, it would likely be a small minyan in an area devoid of other Jews. Additionally, Hillel feared anti Jewish laws and persecution forbidding gathering for prayers. Moreover, back then, global communication was unreliable and difficult. Therefore Hillel adopted the simple calculation for these prayers. On the other hand, Hillel employed Rav Adda’s figures for intercalation since for in this specific regard Rav Adda’s numbers were also simple to use (having 7 leap years in a 19 year cycle is not complicated) and even more accurate.
Hillel couldn’t predict how long the Jews would be in exile and he had to prepare for the worst. Out of the two systems Rav Adda’s only creates an extra day every 216 years while Shmuel’s does so every 128 years. I don’t think Hillel thought the exile would last for more than a few hundred years at worst and thus rav adda’s formulation would be just fine – at worst it would lose one or two days, but nothing serious to make the holidays leave their seasons.
By using both contradicting systems, some problems could occur. As we will explain later, Birkat Hachammah is said at the eve of the Tekufat Nissan (or the spring season). We also know from halacha that Pesach must occur during the spring season. Therefore, if it is a year when birkat hachamah is recited, it should certainly be said before Pesach begins. However in 1841, bircas hachama was recited on the second day of Chol ha’moed! That means that the first day of Pesach wasn’t in the spring season!
How did this happen? Bircas hachama is calculated based on Shmuel’s Tekufat Nissan and it worked out that Shmuel’s Tekufat Nissan fell during Pesach. But the rule that Pesach must occur in the spring season goes by Rav Adda’s Tekufat Nissan, which is always earlier than Shmuel’s. Therefore, although it seemed like an internal contradiction to recite birkat hachama in the middle of pesach it was really perfectly fine.
There is another really interesting problem that could occur if the system were to continue to a really long time. Tal u’matar is said on the 60th of Tekufat Tishrei, according to Shmuel’s count. Over 1000 years we will have created an extra 7.5 days, and thus the true fall equinox will occur 7.5 days earlier than our calendar will record it. So instead of reciting Tal u’matar 60 days after the true fall equinox, we will be saying it 67.5 days after the true fall equinox because that is 60 days after our calendar says it’s the fall equinox. Now, Rav Adda’s tekufot will also advance over time, but to a small degree. In those same 1000 years, Rav Adda’s seasons will advance only 4.5 days, thus Rav Adda’s calendar will be 3 days behind Shmuel’s and thus closer to the true astronomical dates.
Since Tal u’matar is calculated based on Shmuel, but Pesach is calculated based on Rav Adda – every 1000 years Tal u’matar will get 3 days close to Pesach. In 42,000 years, the date to recite tal U’matar will coincide with Pesach! This is astonishing because the whole purpose of tal u’matar is about the rain which comes during the late fall. It is on Pesach when we stop saying Tal u’matar!
Anyway, have no fear because our current system is going to be replaced way way before 42,000 years.
The Gemara berachot 59b states:
תנו רבנן: הרואה חמה בתקופתה לבנה בגבורתה וכוכבים במסילותם ומזלות כסדרן, אומר ברוך עושה בראשית. ואימת הוי?  אמר אביי: כל עשרים ושמונה שנין, והדר מחזור ונפלה תקופת ניסן בשבתאי באורתא דתלת נגהי ארבע
“Our Rabbis taught: On seeing the sun at its tekufah, the moon at its strength, the stars in their paths, and the Zodiacal constellations in their order, one says Blessed be the Maker of creation. And when does this happen? Abaye said: Every 28 years when the cycle begins again and the Nisan equinox falls into Saturn on the evening of Tuesday, going into Wednesday.”
Abaye’s explanation is based on Shmuel’s calculation that each Tekufah (season) is 91 days and 7.5 hours long. Therefore, 4 seasons, or one solar year, would be 365.25 days (or 365 days and 6 hours). Additionally Abaye’s explanation assumes Rav Yehoshua’s position regarding the creation of the world:
(There is a famous dispute in Gemara Rosh Hashana 1011 when the world was created: Rav Yehoshua says it was Nissan while Rav Eliezer says it was in Tishrei – the Gemara on 12a concludes that we hold like Rav Yehoshua for calculating the tekufot and Rav Eliezer for numerating the years).
The sun and the moon were first set into place on the evening of the fourth day of creation, or in our terms – Tuesday evening at 6:00 PM. That was the first Tekufat Nissan. One solar year later was the second Tekufat Nissan. Since a solar year, according to Shmuel, is 365.25 days – and since 365 comprises 52 weeks plus a remainder of 1.25 days – the second tekufat Nissan occurred 1.25 days later in the week than the first tekufat Nissan. Thus, the second tekufat Nissan was 1 day and 6 hours (or 30 hours) after Tuesday 6:00 PM, which would be midnight 12:00 AM between Wednesday and Thursday.
If you were to keep adding 30 hours to the first Tekufat Nissan (Tuesday 6:00 PM…Wednesday 12:00 AM…Friday 6:00 AM…Saturday 12:00PM…Sunday 6:00 PM…Monday 12:00 AM…Wednesday 6:00 AM…ect…) it would take 28 years until the Tekufat Nissan returned to Tuesday 6:00 PM.
If you notice the pattern, every 4 years the tekufah returns to the same time of the day (6:00 PM). Also, since 1.25 times 4 is 5  Every set of 4 years will start 5 days later in the week. So if the first set of 4 was on a Tuesday, the second set of 4 would be on a Sunday. The third will be on a Friday, the fourth on a Wednesday, the fifth on a Monday, the sixth on Saturday, the seventh on Thursday and finally at the very beginning of the eighth cycle it will be back to Tuesday. So it takes 7 full sets of 4 to return to the same day of the week, hence it takes 28 years.
In a sense this is the sun’s anniversary which we celebrate by making our special birkat haChammah on.
Therefore this April 8, 2009 in the morning we will be saying Birkat Hachammah
 Birkat HaChammah is said the morning following the spring equinox (also known as the vernal equinox)
 Essentially the prayer is just the one bracha, but many have the custom to add in relevant psalms.
 A minyan of 10 isn’t needed but it is preferably to say the blessing in a large group so as to fulfill B’ Rov Am.
 It should be recited while standing, but may be recited while sitting.
 It may be recited through a window.
 The blessing should be said as early as possible after Netz HaChama. Many have the custom to pray shacharit at Netz that morning and then say the bracha right afterwards.
 In order to say the blessing with the Shem and malchut one must say it before the end of the 3rd hour of the day.
 If the sun is covered with clouds for the entire first 3 hours of the day, the blessing may still be said so long as its outline can been seen through the clouds or if any part of the sun is visible.
 If the sun is entirely covered with clouds  and one is not able to say it before 3 hours into the day, he may say the bracha without Shem and Malchut all day.
 There is no shecheyanu. Some have the custom to wear a new shirt and then say shecheyanu on the shirt and patur the sun.
 Women generally make their own bracha, although some have the custom not so. This applies to both Sefardim and Ashkenazim (see Hazon Ovadia: Berachot pg. 485).
 A blind person should either hear the bracha from someone else and answer amen or say it by himself without Shem and Malchut.
http://www.kehillaton.com/en/docs/birkat_hachama.pdf
Back
to top
Questions or comments?
send me an email