Birkat Hachama

Birkat Hachama
Sunrise in Bel-Air, California on Wednesday, April 8, 2009, the date of Birkat Hachama
Official name	Hebrew: ברכת החמה (Birkat Hachammah or Birkas Hachoma). Translation: "Blessing of the (because of the) Sun"
Observed by	Judaism and Jews
Type	Judaism
Significance	Traditionally, the coincidence of the Sun's return to its location during the Creation of the world at the time of the week at which it was created
Observances	Recitation of blessing, along with various Sun-related biblical texts, while outdoors and in the presence of the Sun
Begins	Wednesday April 8th, every 28 years, dawn
Ends	3rd hour of the day
Frequency	every 28 years (next occurrence: April 8, 2037)

Hebrew: ברכת החמה (Birkat Hachammah or Birkas Hachoma).

Birkat Hachama (ברכת החמה, "Blessing of the Sun") refers to a rare Jewish blessing that is recited to the Creator, thanking Him for creating the sun. The blessing is recited when the sun completes its cycle every 28 years on a Tuesday at sundown. Jewish tradition says that when the Sun completes this cycle, it has returned to its position when the world was created. Because the blessing needs to be said when the sun is visible, the blessing is postponed to the following day, on Wednesday morning.

According to Judaism, the Sun has a 28-year solar cycle known as machzor gadol (מחזור גדול, "the great cycle"). A solar year is estimated as 365.25 days and the "Blessing of the Sun", being said at the beginning of this cycle, is therefore recited every 10,227 (28 times 365.25) days. The last time that it was recited was on April 8, 2009 (14 Nisan 5769 on the Hebrew calendar.

From an astronomic point of view, there is nothing special to these dates; e.g. the sun, moon, planets and stars will not be aligned in any specific pattern. The text of the blessing itself is as follows:

The primary source for the institution of Birkat Hachama is a Beraita mentioned in the Talmud:

The middle of this clause in the beraita (elided here) speaks of other astronomical phenomena, the interpretation of which is ambiguous. The Gemara clarifies when the 'turning point' (תקופה) mentioned in the beraita occurs:

Next, the gemara explains the basis of the 28 years:

This explanation provided by Abaye is based on a ruling of Shmuel also mentioned in the Talmud:

Shmuel's calculations, however, are imprecise because the earth does not travel around the sun with a constant speed. His imprecision, according to Abraham ibn Ezra, was a function of the desire of the time to avoid the necessity of manipulating fractions.