Jewish Calendar

The question is often asked as to whether the Jewish calendar is lunar or solar. The correct answer is that it is both.

The individual months are determined by the monthly cycle of the moon. There are usually six months of twenty-nine day, and six months that are thirty days. This would give a lunar year 354 days.

But the solar aspect of the calendar forces the holiday of Pesach to be celebrated in spring. It is also called, חג האביב, the Holiday of Spring. And if spring begins around March twenty-first, Pesach must be celebrated after this date.

This caused the Rabbis to set up a system that there would be seven leap years every nineteen years. The leap year consisted of an extra month of Adar, so that in leap years, the lunar calendar would have 384 days, to even things out.

This also demonstrates the power given to the Rabbis. There is a connection between the earthly court and the heavenly court. When the earthly court decided something, the heavenly court would concur.

The case in point was the establishment of the leap year before there was a set calendar. Rav Moshe Tendler once explained this very succinctly. He said that when we get close to the holiday of Purim, it is determined whether on the fifteenth of the month we will be eating Matzah or Hamentaschen!

This all was up to the discretion of the Sanhedrin, and endorsed by Heaven. We see the important role of the Rabbis and the authority given to them by Hashem. All of this began in Egypt when the month of Nissan was designated as the first of the months for the Jewish people.