Editing Hebrew calendar (section)

===Years===
====New year====
[[File:Liten askenasisk sjofar 5380.jpg|right|thumb|A ''[[shofar]]'' made from a ram's horn is traditionally blown in observance of [[Rosh Hashanah]], the beginning of the Jewish civic year.]]

The Hebrew calendar year conventionally begins on [[Rosh Hashanah]], the first day of [[Tishrei]]. However, the Jewish calendar also defines several additional new years, used for different purposes. The use of multiple starting dates for a year is comparable to different starting dates for civil "calendar years", "tax or [[fiscal year]]s", "[[academic year]]s", and so on. The ''[[Mishnah]]'' (c. 200 CE) identifies four new-year dates:

<blockquote>The 1st of Nisan is the new year for kings and festivals. The 1st of Elul is the new year for the [[cattle tithe]], Rabbi Eliezer and Rabbi Shimon say on the first of Tishrei. The [[Rosh Hashanah|1st of Tishri]] is the new year for years, of the [[Shmita]] and Jubilee years, for planting and for vegetables. The 1st of [[Shevat]] is the new year for trees—so the school of Shammai, but the school of Hillel say: On the [[Tu Bishvat|15th thereof]].<ref>[[s:Translation:Mishnah/Seder Moed/Tractate Rosh Hashanah/Chapter 1/1|Rosh Hashanah 1:1]]</ref></blockquote>

Two of these dates are especially prominent:
* 1 Nisan is the ''ecclesiastical new year'', i.e. the date from which months and festivals are counted.<ref>''Hebrew-English Bible,'' {{bibleverse||Exodus|12:2|HE}} "This month [Aviv/[[Nisan]]] shall be unto you the beginning of months; it shall be the first month of the year to you."</ref> Thus [[Passover]] (which begins on 15 Nisan) is described in the Torah as falling "in the first month",<ref>''Hebrew-English Bible,'' {{bibleverse||Leviticus|23:5|HE}}</ref> while [[Rosh Hashana]] (which begins on 1 Tishrei) is described as falling "in the seventh month".<ref>''Hebrew-English Bible,'' {{bibleverse||Leviticus|23:24|HE}}</ref>
* 1 Tishrei is the ''civil new year'', and the date on which the year number advances. This date is known as [[Rosh Hashanah]] ({{lit|head of the year}}).  Tishrei marks the end of one ''agricultural'' year and the beginning of another,<ref>''Hebrew-English Bible,'' {{bibleverse||Exodus|23:16|HE}}, {{bibleverse-nb||Exodus|34:22|HE}}</ref> and thus 1 Tishrei is considered the new year for most agriculture-related commandments, including [[Shmita]], Yovel, [[Maaser Rishon]], [[Maaser Sheni]], and [[Maaser Ani]].

For the dates of the Jewish New Year see [[Jewish and Israeli holidays 2000–2050]].

====Anno Mundi====
{{Main|Anno Mundi}}
[[File:Creation of Light Detail 2.png|right|thumb|The Jewish calendar's reference point is traditionally held to be about one year ''before'' the [[Genesis creation myth|Creation]] of the world.]]

The Jewish year number is generally given by ''{{lang|la|Anno Mundi}}'' (from [[Latin]] "in the year of the world", often abbreviated ''AM'' or ''A.M.''). In this [[calendar era]], the year number equals the number of years that have passed since the [[Genesis creation narrative|creation of the world]], according to an interpretation of [[Biblical]] accounts of the creation and subsequent history. From the eleventh century, ''anno mundi'' dating became the dominant method of counting years throughout most of the world's Jewish communities, replacing earlier systems such as the [[Seleucid era]].<ref name=Jones/><ref>{{Cite book |url=https://books.google.com/books?id=0umDqPOf2L8C&pg=PA87 |title=The Easter Computus and the Origins of the Christian Era |author=Alden A. Mosshammer|year= 2008 |isbn=9780191562365|pages=87–89 |publisher=OUP Oxford }}</ref>
As with {{lang|la|[[Anno Domini]]}} (A.D. or AD), the words or abbreviation for {{lang|la|Anno Mundi}} (A.M. or AM) for the era should properly ''precede'' the date rather than follow it. 

The reference junction of the Sun and the Moon (Molad 1) is considered to be at 5 hours and 204 halakim, or 11:11:20&nbsp;p.m., on the evening of Sunday, 6 October 3761 BCE.<ref>Edgar Frank, ''Talmudic and Rabbinical Chronology: The System of Counting Years in Jewish Literature,'' (New York: Philip Feldheim, Publisher, 1956)</ref> According to rabbinic reckoning, this moment was ''not'' [[Creation according to Genesis|Creation]], but about one year "before" Creation, with the new moon of its first month (Tishrei) called ''molad tohu'' (the mean new moon of chaos or nothing). It is about one year ''before'' the traditional Jewish [[Dating Creation|date of Creation]] on 25 Elul AM 1,{{efn|The significance of 25 Elul derives from Adam and Eve being created on the sixth day of creation, 1 Tishrei AM 2. In this view, AM 2 is the actual first year of the world, while AM 1 is a "placeholder" year, so that calendar dates can be assigned to the days of creation.}} based upon the ''Seder Olam Rabbah''.{{efn|A minority opinion places Creation on 25 Adar AM 1, six months earlier, or six months after the modern epoch.}} Thus, adding 3760 before [[Rosh Hashanah]] or 3761 after to a [[Julian calendar]] year number starting from 1 CE will yield the Hebrew year. For earlier years there may be a discrepancy; ''see [[Missing years (Jewish calendar)]]''.

{{anchor|writing}}In Hebrew there are two common ways of writing the year number: with the thousands, called {{lang|he|לפרט גדול}} ("major era"), and without the thousands, called {{lang|he|לפרט קטן}} ("minor era"). Thus, the current year is written as <span style="direction:rtl;">'''{{lang|he|{{#time:xhxjY}}}}'''</span> &lrm;({{#time:xjY}}) using the "major era" and <span style="direction:rtl;">'''{{lang|he|{{#invoke:string|sub|{{#time:xhxjY}}|3|-1}}}}'''</span> &lrm;({{#expr:{{#time:xjY}}mod1000}}) using the "minor era".

====Cycles of years====
Since the Jewish calendar has been fixed, leap months have been added according to the [[Metonic cycle]] of 19 years, of which 12 are common (non-leap) years of 12 months, and 7 are leap years of 13 months. This 19-year cycle is known in Hebrew as the ''Machzor Katan'' ("small cycle").

Because the Julian years are {{frac|365|1|4}} days long, every 28 years the weekday pattern repeats. This is called the sun cycle, or the ''Machzor Gadol'' ("great cycle") in Hebrew. The beginning of this cycle is arbitrary. Its main use is for determining the time of [[Birkat Hachama]].

Because every 50 years is a Jubilee year, there is a jubilee (''yovel'') cycle. Because every seven years is a sabbatical year, there is a seven-year release cycle. The placement of these cycles is debated. Historically, there is enough evidence to fix the sabbatical years in the [[Second Temple Period]].<ref>B. Zuckermann, ''A Treatise on the Sabbatical Cycle and the Jubilee'', trans. A.&nbsp;Löwy. New York: Hermon Press, 1974.</ref> But it may not match with the sabbatical cycle derived from the biblical period; and there is no consensus on whether or not the Jubilee year is the fiftieth year or the latter half of the forty ninth year.

Every 247 years, or 13 cycles of 19 years, form a period known as an ''iggul'', or the ''Iggul of [[Nahshon ben Zadok|Rabbi Nahshon]]''. This period is notable in that the precise details of the calendar almost always (but not always) repeat over this period. This occurs because the ''molad'' interval (the average length of a Hebrew month) is 29.530594 days, which over 247 years results in a total of 90215.965 days. This is almost exactly 90216 days – a whole number and multiple of 7 (equalling the days of the week). So over 247 years, not only does the 19-year leap year cycle repeat itself, but the days of the week (and thus the days of Rosh Hashanah and the year length) typically repeat themselves.<ref>Nadia Vidro, "The Origins of the 247-Year Calendar Cycle", ''Aleph'', '''17''' (2017), 95–137 [https://doi.org/10.2979/aleph.17.1.0095 doi link].</ref><ref>Dov Fischer, [https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4364371 The Enduring Usefulness of the Tur’s 247-year Calendar Cycle (Iggul of Rabbi Nachshon)]</ref>