The Gregorian calendar is a method of calculating the dates used by most of the world. It was sponsored by Pope Gregory XIII 1582 as a corrected version of the Julian calendar. It is a solar-based calendar in which dates represent the position of the Earth in its revolt around the sun.
The Hebrew / Jewish calendar is quite different from the Gregorian or Julian calendar. It is a moon-based calendar, which depends on the lunar phase cycles. It is also adjusted by adding intercalary months (that is, the thirteenth month in certain years) to make lunar cycles in sync with the solar year.
Trying to understand the holy day dates in the Gregorian calendar can be very difficult. For example, the Feast of Trumpets (Rosh Hashanah) falls on the date of the Hebrew calendar of Cherry 1. One might wonder why Tishri 1 fell in some years in early September, while it may sometimes be late for October. A basic understanding of the modified lunar calendar used by the Jewish people provides answers.
In this chapter, I will explain how to reconcile the discrepancies between the number of days in Jewish and Gregorian calendars. The calculations used may seem somewhat frightening, with long decimal places and many steps, but they are really very straightforward. The acquisition of knowledge in the Jewish calendar will greatly help to understand why the Holy Days do not occur at the same time in our calendar each year. In addition, learning a completely different way of calculating months and years can be interesting.
The main points to note are that the lunar calendar has 29.53 days per month. Twelve months is approximately 354 days, less than 11 or 12 days in the Gregorian calendar. To make up for this difference, the Jewish calendar adds a thirteenth month in seven years out of every nineteen, with the “lunar calendar” (calendar) and the Gregorian calendar coming almost every thirteen years. The chart below shows the number of months per year on the Hebrew calendar over the current nineteen cycle, with the corresponding calendar year after.
Year / # months
The second part of this series will determine the compatibility of days between shared calendars.