On which day of the Hebrew calendar did Christopher Columbus first sail for the Americas?

**Cristopher Columbus** began his historically famous first voyage to the Americas (or ** Indies** as he wrote in his trip log) half an hour before sunrise on

This date corresponded to **10 Av 5252H**, which appears to be the day immediately following the much dreaded Jewish observance of

The ** Weekly Question** deeply appreciates correspondent

On which day of the Hebrew calendar did Christopher Columbus first set foot in the Americas?

**Cristopher Columbus** began his historically famous first voyage to the Americas (or ** Indies** as he wrote in his trip log) half an hour before sunrise on

This date corresponded to **10 Av 5252H**, which appears to be the day immediately following the much dreaded Jewish observance of

According to the entry in his preserved ship's log, he first set foot in the Americas on **Friday 12 October 1492j**, which date corresponded to **21 Tishrei 5253H**.

If, as some speculations imply, the trans-Atlantic voyage included some passengers of Jewish origin, then these travellers would have arrived in the Americas on the festival day known as ** Hoshannah Rabbah**, and celebrated

Intriguingly, the first Columbus voyage to the Americas took exactly **10 complete weeks**.

A translated version of the Columbus voyage log of **1492j** may be found at

Medieval Sourcebook: Christopher Columbus: Extracts From Journal
.

Assuming that

Tishrei1 could be postponed from 1 up to 6 days from the day of themolad of Tishrei, what then would be the length in days of the longest single Hebrew year?

The total number of ways in which **1 up to 6 weekdays** may be selected for postponement purposes is **126**.

Properties of Hebrew Year Periods - Part 1 indicates that without any of the ** dehiyyot**, the longest single Hebrew year would be

For reasons which are presently quite obscure, it appears that as long as at least **one weekday** has been selected for the postponement of ** Tishrei**, then no matter how many

The ** Weekly Question** will very much appreciate receiving any mathematical analysis of this rather intriguing Hebrew calendar phenomenon.

Assuming that

Tishrei1 could be postponed from 1 up to 6 days from the day of themolad of Tishrei, what then would be the length in days of the longest 12-month Hebrew year?

The total number of ways in which **1 up to 6 weekdays** may be selected for postponement purposes is **126**.

Properties of Hebrew Year Periods - Part 1 indicates that without any of the ** dehiyyot**, the longest

For reasons which are presently quite obscure, it appears that as long as at least **two consecutive weekdays** have been selected for the postponement of ** Tishrei**, then no matter how many

However, when at least one or more non-consecutive weekdays are selected for the postponement of ** Tishrei**, then the longest possible

The largest number of non-consecutive weekdays which can be selected from the **seven weekdays** is **3**.

The ** Weekly Question** will very much appreciate receiving any mathematical analysis of this rather intriguing Hebrew calendar phenomenon.

Correspondent **Ben Dreyfus** suggested the following answer.

Thank youI'm assuming from your answer to Question 243 that the postponement you're talking about is an extension of Lo ADU, saying that (e.g.) Rosh Hashanah must always be on Tuesday. In that case, i'm going with 357 days (exactly 51 weeks) as the longest length of a 12-month year, just as 385 days (55 weeks) is the longest 13-month year. (If there is only one day of the week when RH can fall, then every year must have an integer number of weeks.) Ben Dreyfus

Assuming that

Tishrei1 could be postponed from 1 up to 6 days from the day of themolad of Tishrei, what then would be the length in days of the shortest 12-month Hebrew year?

The total number of ways in which **1 up to 6 weekdays** may be selected for postponement purposes is **126**.

Properties of Hebrew Year Periods - Part 1 indicates that without any of the ** dehiyyot**, the shortest

For reasons which are presently quite obscure, it appears that as long as at least **four consecutive weekdays** have been selected for the postponement of ** 1 Tishrei**, then no matter how many

The ** Weekly Question** will very much appreciate receiving any mathematical analysis of this rather intriguing Hebrew calendar phenomenon.

Relative to 5766H (in 2005g), when last was

Dehiyyah B'TU'TKPTinvoked?

** Dehiyyah B'TU'TKPT** is invoked whenever the

The ** molad of Tishrei 5766H** is calculated as being

Since **5765H** was a **13-month year**, ** Dehiyyah BeTU'TeKaPoT** is invoked, postponing

The *Dehiyyot* and The *Qeviyyot* show that ** Dehiyyah B'TU'TKPT** is invoked a total of

That makes ** Dehiyyah B'TU'TKPT** the least often used rule for postponing the first day of

Relative to **5766H (in 2005g)**, ** Dehiyyah B'TU'TKPT** was last invoked for

Relative to 5766H (in 2005g), when next will

Dehiyyah B'TU'TKPTbe invoked?

** Dehiyyah B'TU'TKPT** is invoked whenever the

The ** molad of Tishrei 5766H** is calculated as being

Since **5765H** was a **13-month year**, ** Dehiyyah BeTU'TeKaPoT** is invoked, postponing

The *Dehiyyot* and The *Qeviyyot* show that ** Dehiyyah B'TU'TKPT** is invoked a total of

That makes ** Dehiyyah B'TU'TKPT** the least often used rule for postponing the first day of

Relative to **5766H (in 2005g)**, ** Dehiyyah B'TU'TKPT** was last invoked

Relative to **5766H (in 2005g)**, ** Dehiyyah B'TU'TKPT** will next be invoked

Incidentally, it is entirely coincidental that the answer to ** Weekly Question 247** happens to be "

The next question was asked and solved by correspondent **Nachum Dershowitz**.

How far apart can be two consecutive invocations of

Dehiyyah B'TU'TKPT?

** Dehiyyah B'TU'TKPT** is invoked whenever the

The ** molad of Tishrei 5766H** is calculated as being

Since **5765H** was a **13-month year**, ** Dehiyyah BeTU'TeKaPoT** is invoked, postponing

Relative to **5766H (in 2005g)**, ** Dehiyyah B'TU'TKPT** was last invoked

The *Dehiyyot* and The *Qeviyyot* show that ** Dehiyyah B'TU'TKPT** is invoked a total of

That makes ** Dehiyyah B'TU'TKPT** the least often used rule for postponing the first day of

Two consecutive invocations of ** Dehiyyah B'TU'TKPT** can occur either

SeparationsB'TU'TKPT | |
---|---|

SEPARATION | OCCURENCES |

78 | 819 |

98 | 575 |

169 | 457 |

247 | 1,531 |

345 | 330 |

Please note that the very last occurence of ** Dehiyyah B'TU'TKPT** in the full Hebrew calendar cycle is separated by

Assuming that no change ever takes place to any of the Hebrew, Gregorian, or Julian calendars, then the ** second** full Hebrew calendar cycle theoretically begins at the start of Hebrew year

Many thanks to correspondent **Nachum Dershowitz** for suggesting the question, and to both correspondents **Nachum Dershowitz** and **Ari M. Brodsky** for sharing their correct answers with the ** Weekly Question**.

Between which pair of Hebrew years does each of the possible 5

B'TU'TKPTseparations first occur?

** Dehiyyah B'TU'TKPT** is invoked whenever the

The ** molad of Tishrei 5766H** is calculated as being

Since **5765H** was a **13-month year**, ** Dehiyyah B'TU'TKPT** is invoked, postponing

*Dehiyyot* and The *Qeviyyot* show that ** Dehiyyah B'TU'TKPT** is invoked a total of

** Dehiyyah B'TU'TKPT** the least often used rule for postponing the first day of

Two consecutive invocations of ** Dehiyyah B'TU'TKPT** can occur either

SeparationsB'TU'TKPT | |||
---|---|---|---|

SEPARATION | OCCURENCES | 1st Time | 1st End |

78 | 819 | 78H | 153H |

98 | 575 | 575H | 647H |

169 | 457 | 153H | 322H |

247 | 1,531 | 400H | 647H |

345 | 330 | 1,239H | 1,584H |

Correspondent **Ari M. Brodsky** shared a number of other interesting features pertaining to Hebrew year **5766H** begun on ** Tuesday 4 October 2005g**.

What are at least 3 other calendar oriented features relevant to Hebrew year 5766H?

Correspondent **Ari M. Brodsky** noted the following features relevant to Hebrew year **5766H (started Tue 4 Oct 2005g)**.

1) Beginning on Tuesday, the year is 354 days long causing its 12 months to alternate exactly between 30 and 29 day months. About 6.2% of all of the years in the full Hebrew calendar cycle of 689,472 years are 12-month years beginning on Tuesday. 2) Dechiyyah B'TU'TKPT postponed the beginning of 5766H. 3) For observant Jews living in Canada, there are no three consecutive working days in October 2005g, due to the arrangement of the High Holiday Festivals and the fact that Thanksgiving falls during the same week as Yom Kippur. 4) We read from 3 Torah scrolls on Shabbat Rosh Hodesh Hanukka. The regular parsha that day is Mikketz, which is quite long as well. 5) There are only 6 days of Chanukka in 2005g. 6) 5766H is the 9th year of the 19-year Jewish calendar cycle GUChADZT. Until the end of Shevat 5766H (February 2006), we are within the “late-year” period, when all Jewish calendar dates and holidays fall at their latest possible points in the solar year (i.e. relative to the civil calendar). 7) February 2006 does not contain the first day of any Jewish month. 8) All possible “double parashiyyot” are combined during 5766H. As well, Parashat Vayyeilekh will be read on two Shabbat mornings during the year – on the first Shabbat of the year (5 Tishrei / October 8, 2005g) and on the last Shabbat of the year (23 Elul / September 16, 2006g). 9) Yom HaAtzmaut is actually celebrated on 5 Iyyar, for a change. 10) There will be a discrepancy in Torah readings between Israel and the Diaspora, for several weeks after Shavuot, due to the second day of Shavuot falling on Shabbat. 11) On the evening of 4 Kislev, (December 4), Diaspora Jews begin praying for rain. That certainly makes for an exciting year! Ari Brodsky

Thank you correspondent **Ari M. Brodsky** for sharing these wonderful observations.

The **7th** fact notes that no Hebrew month begins in **February 2006g**, thereby suggesting the next question.

First Begun 21 Jun 1998 First Paged 2 Feb 2005 Next Revised 18 Dec 2005