Jewish Calendar Basics

Then God said, “Let lights appear in the sky to separate the day from the night. Let them be signs to mark the seasons, days, and years. Genesis 1:14 (New Living Translation, NLT)

Today marks Rosh Hashanah, or the start of the Jewish year. In case you haven’t noticed, there are some distinct differences between the Hebrew calendar and the Gregorian, or secular, calendar that the world goes by. The Gregorian calendar is based upon the solar system, or the orbit of the Earth around the sun. However, the Hebrew calendar is a solar-lunar calendar, meaning it is based on the Earth’s orbital travel around the sun as well as the moon’s orbit around the Earth. The lunar movement sets the months, but the sun establishes seasons.

The issue is that the two calendars have a different number of days in a year. The solar calendar that most of us use has 365.25 days and the partial day is accounted for every four years when an extra day is added to February- leap day. On the other hand, the Jewish calendar has just 354 days based on the moon’s orbit. To keep the Jewish calendar properly aligned with the seasons, which is based on the sun, an extra month is added occasionally to even it out.

Another difference is that the Jewish calendar begins at the time that the Jews believe Adam and Eve were created, while we base the secular calendar on the believed time of Christ’s birth, with it being separated into BC (Before Christ) and AD (anno Domini-Latin for “in the year of the Lord”, or as it was originally noted anno Domini nostri Jesu Christi- “in the year of our Lord Jesus Christ”). So the current secular year is 2022 A.D., or 2,022 after Christ. The current Jewish year that begins at the conclusion of Rosh Hashanah is 5783, which measures what the Jews believe is all of time since creation.

Another difference in the Jewish and secular way of measuring time is the concept of when each day starts. The secular day begins and ends at midnight. On the Jewish calendar, a day begins at sunset. This is because the Bible records in Genesis that the evening and then morning marked the first day.

God called the light “day,” and the darkness he called “night.” And there was evening, and there was morning—the first day. Genesis 1:5 (New International Version, NIV)

Why do these differences matter? It is important to understand these differences when we read the Bible, since it was written by Jews and in the context of Jewish culture. And it helps us to more clearly note the workings of God, because He likes to do special things around the Jewish holy days and feast times that He set using the Hebrew calendar.

So, today, as we mark Rosh Hashanah, which starts the Feast of Trumpets, and the beginning of the Hebrew year 5783, expect God to do amazing things in the Earth!