How well does the calendar correspond to the solar year?
rabbis recognized long ago that the calendar gains 1h 485p in every 19-year cycle, adding up to a day every 300 years or so. This was important to the rabbis in scheduling certain rituals that are based on the solar year rather than the lunar year. We can see this effect when we examine the dates of Rosh Hashanah over time. Rabbi Hillel II developed the Jewish calendar in the Jewish year 4119. Using his calendar methods as described above, and artificially assuming that the Gregorian calendar we use today was in effect at that time, the date of Rosh Hashanah ranged from August 29 to September 28 between the years 4100 and 4200 (the 42nd century). In the present Jewish century (the 58th), the dates of Rosh Hashanah range from September 5 to October 5, a gain of 6 or 7 days. This is considerably more accurate than the Julian calendar used by Christians in Rabbi Hillel’s time (which had to be corrected by 11 days a few centuries ago), but you can see that it is gaining some time. The disc
