From Wikipedia
Birkat ha-Hammah (ברכת החמה, also: ha-Chamah, Hahammah, Hachammah), is
Hebrew for "The Blessing of the
Sun."
It is a special
Jewish prayer recited once every twenty-eight years, the period of the
solar cycle. Jewish law stipulates that the prayer be said every 10,227 (28 times 365.25) days. The next date set is April 8, 2009 (
Hebrew year 5769).
According to the
Babylonian Talmud (tractate
Berachot 59b), at these times the
Sun returns to the position that it had when the Universe was first created. The explanation is that if the year were exactly 365.25 days, the Sun's equinox times would be at the same time in the week every 28 years (28 times 0.25 days equals 7 days). The tradition is that the Sun was created in its Spring equinox position, at the first hour of the night before the fourth day of Creation. Whenever the equinox is thought to occur at that same time of the week, the Sun is said to have returned to its original position.
The
solar cycle is a 28-year cycle of the
Julian calendar with respect to the
week. It occurs because
leap years occur every 4 years and there are 7 possible days to start a
leap year, making a 28-year sequence.
This cycle also occurs in the
Gregorian calendar, but it is interrupted by years such as 1800, 1900, 2100, 2200, 2300 and 2500, which are divisible by four but which are
common years. This interruption has the effect of skipping 16 years of the solar cycle between February 28 and March 1. Because the Gregorian cycle of 400 years has exactly 146,097 days, i.e. exactly 20,871 weeks, one can say that the Gregorian so-called solar cycle lasts 400 years.
Calendar years are usually marked by
Dominical letters indicating the first
Sunday in a new year, thus the term solar cycle can also refer to a repeating sequence of Dominical letters.
Unless a year is not a leap year due to Gregorian exceptions, a sequence of calendars is reused every 28 years.
The name
solar cycle comes from
Sunday, the traditional
first day of the week.
The Qumran calendar
See also:
Enoch calendar and
Qumran calendrical texts
Many of the Dead Sea (Qumran) Scrolls have references to a unique calendar, used by the people there, who are often assumed to be Essenes.
The year of this calendar used the ideal Mesopotamian calendar of twelve 30-day months, to which were added 4 days at the equinoxes and solstices (cardinal points), making a total of 364 days.
There was some ambiguity as to whether the cardinal days were at the beginning of the months or at the end, but the clearest calendar attestations give a year of four seasons, each having three months of 30, 30, and 31 days with the cardinal day the extra day at the end, for a total of 91 days, or exactly 13 weeks. Each season started on the 4th day of the week (Wednesday), every year. (Ben-Dov,
Head of All Years, pp. 16–17)
With only 364 days, it is clear that the calendar would after a few years be very noticeably different from the actual seasons, but there is nothing to indicate what was done about this problem. Various suggestions have been made by scholars. One is that nothing was done and the calendar was allowed to change with respect to the seasons. Another suggestion is that changes were made irregularly, only when the seasonal anomaly was too great to be ignored any longer. (Ben-Dov,
Head of All Years, pp. 19–20)
The writings often discuss the moon, but the calendar was not based on the movement of the moon any more than indications of the phases of the moon on a modern western calendar indicate that that is a lunar calendar.
