Karaites use the lunar month and the solar year, but the Karaite calendar differs from the current Rabbinic calendar in a number of ways. The Karaite calendar is identical to the Rabbinical calendar used before the Sanhedrin changed the Rabbinic calendar from the lunar, observation based calendar, to the current mathematically based calendar used in Rabbinic Judaism today.
In the lunar Karaite calendar, the beginning of each month, the Rosh Chodesh, can be calculated, but is confirmed by the observation in Israel of the first sightings of the new moon. This may result in an occasional variation of a maximum of one day, depending on the inability to observe the new moon. The day is usually "picked up" in the next month.
The addition of the leap month (Adar II) is determined by observing in Israel the ripening of barley at a specific stage (defined by Karaite tradition) (called aviv), rather than using the calculated and fixed calendar of Rabbinic Judaism. Occasionally this results in Karaites being one month ahead of other Jews using the calculated Rabbinic calendar. The "lost" month would be "picked up" in the next cycle when Karaites would observe a leap month while other Jews would not.
Furthermore, the seasonal drift of the Rabbinic calendar is avoided, resulting in the years affected by the drift starting one month earlier in the Karaite calendar.
Also, the four rules of postponement of the Rabbinic calendar are not applied, since they are not mentioned in the Tanakh. This can affect the dates observed for all the Jewish holidays in a particular year by one day.
In the Middle Ages many Karaite Jews outside Israel followed the calculated Rabbinic calendar, because it was not possible to retrieve accurate aviv barley data from the land of Israel. However, since the establishment of the State of Israel, and especially since the Six Day War, the Karaite Jews that have made aliyah can now again use the observational calendar.
Famous quotes containing the word calendar:
“To divide ones life by years is of course to tumble into a trap set by our own arithmetic. The calendar consents to carry on its dull wall-existence by the arbitrary timetables we have drawn up in consultation with those permanent commuters, Earth and Sun. But we, unlike trees, need grow no annual rings.”
—Clifton Fadiman (b. 1904)