The Nisan Descent
The Nisan Descent

by Remy Landau
=================================

Whenever the first day of the month of Nisan coincides with any day past the 5th day of March, but in the Month of March, then the first day of each subsequent Hebrew month, until the end of the Hebrew year, coincides with its corresponding Gregorian day in a descending sequence. The sequence is an arithmetical progression in which the difference between each term is -1.

The descending sequence of the corresponding Gregorian days will be referred to as the Nisan descent.

The First Nisan Descent

The following table for the year 3H shows the first occurrence of the Nisan descent.

Month Moment of Molad First Day Chodesh
Tishrei
`Tue 22h 48m 12hl`
`  Thu 18 Aug -3758g `
Heshvan
`Thu 11h 32m 13hl`
` *Sat 17 Sep -3758g `
Kislev
`Sat  0h 16m 14hl`
`  Sun 16 Oct -3758g `
Tevet
`Sun 13h  0m 15hl`
`  Mon 14 Nov -3758g `
Shevat
`Tue  1h 44m 16hl`
`  Tue 13 Dec -3758g `
`Wed 14h 28m 17hl`
` *Thu 12 Jan -3757g `
`Fri  3h 13m  0hl`
` *Sat 11 Feb -3757g `
Nisan
`Sat 15h 57m  1hl`
`  Sun 12 Mar -3757g `
Iyar
`Mon  4h 41m  2hl`
` *Tue 11 Apr -3757g `
Sivan
`Tue 17h 25m  3hl`
`  Wed 10 May -3757g `
Tammuz
`Thu  6h  9m  4hl`
` *Fri  9 Jun -3757g `
Av
`Fri 18h 53m  5hl`
`  Sat  8 Jul -3757g `
Elul
`Sun  7h 37m  6hl`
` *Mon  7 Aug -3757g `

The Earliest Possible Nisan Descent

The earliest possible Nisan descent is formed when the first day of Nisan coincides with the 6th day of March. That first happened for 1 Nisan 9H, corresponding to 6 March -3751g. It last happened in 4424H, corresponding to 664g, and will not reoccur until March 6, 81993H (78234g). The following table shows the moladot for 9H.

Month Moment of Molad First Day Chodesh
Tishrei
`Fri 17h 52m 15hl`
`  Sat  9 Sep -3752g `
Heshvan
`Sun  6h 36m 16hl`
` *Mon  9 Oct -3752g `
Kislev
`Mon 19h 20m 17hl`
` *Wed  8 Nov -3752g `
Tevet
`Wed  8h  5m  0hl`
` *Fri  8 Dec -3752g `
Shevat
`Thu 20h 49m  1hl`
`  Sat  6 Jan -3751g `
`Sat  9h 33m  2hl`
` *Mon  5 Feb -3751g `
Nisan
`Sun 22h 17m  3hl`
`  Tue  6 Mar -3751g `
Iyar
`Tue 11h  1m  4hl`
` *Thu  5 Apr -3751g `
Sivan
`Wed 23h 45m  5hl`
`  Fri  4 May -3751g `
Tammuz
`Fri 12h 29m  6hl`
` *Sun  3 Jun -3751g `
Av
`Sun  1h 13m  7hl`
`  Mon  2 Jul -3751g `
Elul
`Mon 13h 57m  8hl`
` *Wed  1 Aug -3751g `

The Last Nisan Descent

The last time, before Thursday March 6, 81993H (78234g), that the first day of Nisan will coincide with any day in the month of March will be in the year 10257H (6497g). The following table shows the first day of Nisan coinciding with the last day of March.

Month Moment of Molad First Day Chodesh
Tishrei
`Fri  1h 58m 10hl`
`  Sat  6 Oct  6496g `
Heshvan
`Sat 14h 42m 11hl`
` *Mon  5 Nov  6496g `
Kislev
`Mon  3h 26m 12hl`
`  Tue  4 Dec  6496g `
Tevet
`Tue 16h 10m 13hl`
`  Wed  2 Jan  6497g `
Shevat
`Thu  4h 54m 14hl`
`  Thu 31 Jan  6497g `
`Fri 17h 38m 15hl`
` *Sat  2 Mar  6497g `
Nisan
`Sun  6h 22m 16hl`
`  Sun 31 Mar  6497g `
Iyar
`Mon 19h  6m 17hl`
` *Tue 30 Apr  6497g `
Sivan
`Wed  7h 51m  0hl`
`  Wed 29 May  6497g `
Tammuz
`Thu 20h 35m  1hl`
` *Fri 28 Jun  6497g `
Av
`Sat  9h 19m  2hl`
`  Sat 27 Jul  6497g `
Elul
`Sun 22h  3m  3hl`
` *Mon 26 Aug  6497g `

Two Consecutive Nisan Descents

The following shows the Nisan descents for two consecutive years, which interestingly enough, are close to our own times.

Month Moment of Molad First Day Chodesh
Tishrei
`Thu  4h  7m  3hl`
`  Thu  2 Oct  1997g `
Heshvan
`Fri 16h 51m  4hl`
` *Sat  1 Nov  1997g `
Kislev
`Sun  5h 35m  5hl`
`  Sun 30 Nov  1997g `
Tevet
`Mon 18h 19m  6hl`
` *Tue 30 Dec  1997g `
Shevat
`Wed  7h  3m  7hl`
`  Wed 28 Jan  1998g `
`Thu 19h 47m  8hl`
` *Fri 27 Feb  1998g `
Nisan
`Sat  8h 31m  9hl`
`  Sat 28 Mar  1998g `
Iyar
`Sun 21h 15m 10hl`
` *Mon 27 Apr  1998g `
Sivan
`Tue  9h 59m 11hl`
`  Tue 26 May  1998g `
Tammuz
`Wed 22h 43m 12hl`
` *Thu 25 Jun  1998g `
Av
`Fri 11h 27m 13hl`
`  Fri 24 Jul  1998g `
Elul
`Sun  0h 11m 14hl`
` *Sun 23 Aug  1998g `

Month Moment of Molad First Day Chodesh
Tishrei
`Mon 12h 55m 15hl`
`  Mon 21 Sep  1998g `
Heshvan
`Wed  1h 39m 16hl`
` *Wed 21 Oct  1998g `
Kislev
`Thu 14h 23m 17hl`
` *Fri 20 Nov  1998g `
Tevet
`Sat  3h  8m  0hl`
` *Sun 20 Dec  1998g `
Shevat
`Sun 15h 52m  1hl`
`  Mon 18 Jan  1999g `
`Tue  4h 36m  2hl`
` *Wed 17 Feb  1999g `
Nisan
`Wed 17h 20m  3hl`
`  Thu 18 Mar  1999g `
Iyar
`Fri  6h  4m  4hl`
` *Sat 17 Apr  1999g `
Sivan
`Sat 18h 48m  5hl`
`  Sun 16 May  1999g `
Tammuz
`Mon  7h 32m  6hl`
` *Tue 15 Jun  1999g `
Av
`Tue 20h 16m  7hl`
`  Wed 14 Jul  1999g `
Elul
`Thu  9h  0m  8hl`
` *Fri 13 Aug  1999g `

Understanding The Nisan Descent

The Nisan descent is easily explained once it is understood that the 5 Hebrew months from Nisan through Av alternate regularly between 30 and 29 days, while the 5 Gregorian months from March through July alternate regularly between 31 and 30 days.

```First  Paged 25 May 1998