Hebrew calendar facts for kids

The Hebrew calendar, also known as the Jewish calendar, is the special calendar used in Judaism. It helps Jewish people know when to celebrate holidays. It also tells them when to read parts of the Torah each week. This calendar is important for big life events too. For example, it sets the date for a Bar Mitzvah or Bat Mitzvah. These events mark when a young person becomes an adult in Judaism. The calendar also helps remember the Yahrzeit, which is the anniversary of a relative's death. Even daily Jewish prayers change based on the Hebrew calendar.

How the Hebrew Calendar Works

The Hebrew calendar is a special kind of lunisolar calendar. This means it uses both the moon and the sun to keep track of time.

Months and the Moon

The months in the Hebrew calendar follow the new moon. A new month starts when the new moon appears.

Years and the Sun

Even though months follow the moon, the holiday of Passover must always be in the spring. Because of this, the years in the Hebrew calendar follow the sun. A solar (sun-based) year is about 365 days long. But twelve lunar (moon-based) months are only about 354 days long.

To make up for this difference, the Hebrew calendar adds an extra lunar month. This happens seven times in every cycle of 19 years. This rule makes the average Hebrew calendar year about the same length as a solar year.

The Seven-Day Week

The seven-day week is also a key part of the Hebrew calendar. It helps figure out the day for Shabbat, the day of rest. The week does not depend on the sun or moon. Instead, it follows a count of seven days that people believe goes back to ancient times.

History of the Hebrew Calendar

Jewish people have used a lunisolar calendar since they left Egypt, according to the Book of Exodus. One of the first commandments they received was to decide when the New Moon began. Soon after, they were told to make sure Passover always happened in the spring.

Month Names Over Time

In the Tanakh (the Hebrew Bible), months were usually numbered instead of named. Only a few month names from before the Babylonian Exile appear in the Tanakh. The names used in the modern Hebrew calendar came from the Babylonian calendar. This happened during the Babylonian Exile in the 6th century BCE.

From Witnesses to Fixed Rules

At first, a new month began when witnesses told the Sanhedrin (a high Jewish court) that they saw the new crescent moon. The Sanhedrin also decided when to add an extra month to keep Passover in the spring. This system is called the Metonic cycle.

After the destruction of the Second Temple in 70 CE, it became hard for the Sanhedrin to meet. So, they made a fixed calendar based on rules. Maimonides fully described this modern Hebrew calendar around the year 1178 CE.

Counting Years: Anno Mundi

In the modern Hebrew calendar, years are counted as Anno Mundi. This is Latin for "year of the world." It follows the traditional count of years since the creation of the world. This story is found in the Genesis. This year is anno mundi 5785.

Karaite Judaism Calendar

The small Karaite Judaism community uses a very similar calendar. However, Karaites still use witnesses to confirm the new crescent moon. They also check the ripening of barley to decide if an extra month is needed. Because of these differences, the Karaite calendar can be slightly different from the main Jewish calendar.

Days of the Hebrew Calendar Week

Months of the Hebrew Calendar Year

More About the Calendar

Understanding a Day and a Week

In the Hebrew calendar, a day starts in the evening. This comes from the Hebrew Bible which says: "And there was evening, and there was morning, one day." So, a day begins at sunset. Sometimes, to be very exact, it starts at nightfall.

When you see a Hebrew calendar printed, it might look like the day starts at midnight, like the Gregorian calendar. But people who use it know that holidays and special dates actually begin the evening before.

Every seventh day in the Hebrew calendar is Shabbat, the day of rest. The week is a cycle of seven days that always ends with Shabbat. The week is not changed by any other calendar rules. The first six days of the week are just called "First day," "Second day," and so on. Only the seventh day has a special name: Shabbat.

The Molad and New Moons

The Hebrew calendar uses something called the molad to figure out the start of months and years. Molad is a Hebrew word that means "birth." It refers to the "birth" of the new moon each month. The modern Hebrew calendar uses a calculated molad. This is the average time it takes for the moon to go from one new moon to the next. This average time is 29 days, 12 hours, 44 minutes, and 3+1⁄3 seconds.

Regular Years and Leap Years

A year with 12 lunar months would be 354 days long. But as we learned, the Hebrew calendar year needs to be about 365 days long, like a solar year. Also, a Hebrew calendar year must have either 12 or 13 full months. It cannot have part of a month.

So, an extra month is added seven times in every 19-year cycle. This is a way of using the Metonic cycle, which was known in ancient times. The extra month is added in years 3, 6, 8, 11, 14, 17, and 19 of the cycle.

Calculating Rosh Hashanah

Rosh Hashanah is the Jewish New Year. Its date is figured out using the molad for the month of Tishrei. There are two main reasons why Rosh Hashanah might be delayed by a day or more:

1. If the molad happens after noon: If the new moon (molad) is calculated to appear after 12:00 noon in Jerusalem, Rosh Hashanah is moved to the next day. This prevents the holiday from starting before the new moon is truly visible in some parts of the world.
2. To avoid certain days: Rosh Hashanah cannot start on a Sunday, Wednesday, or Friday. This rule helps prevent other important holidays, like Yom Kippur (which is 10 days after Rosh Hashanah), from falling right before or after Shabbat. It also stops Hoshana Rabba (the seventh day of Sukkot) from being on Shabbat.

Once the date for this year's Rosh Hashanah is set, the date for next year's is calculated. This is done by adding 12 or 13 molad periods into the future.

How Month Lengths Change

The length of a molad is a little more than 29+1⁄2 days. Since months must have a whole number of days, they usually switch between 30 and 29 days. This makes the average month 29+1⁄2 days long. A 12-month year would then be 354 days.

However, month lengths can change slightly:

• When an extra month is added (in a leap year), it is always the sixth month (counting from Tishrei) and has 30 days.
• If a regular year needs an extra day (making it 355 days long), that day is added to Heshvan (the second month from Tishrei), giving it 30 days.
• If a regular year needs one less day (making it 353 days long), that day is taken away from Kislev (the third month from Tishrei), making it 29 days.

Calendar Months and the Real New Moon

The first day of a Hebrew calendar month is called Rosh Hodesh (רׂאשׁ חוֹדֶש‎). This day is usually close to the actual astronomical new moon. But it's not always exactly on it. There are two main reasons for this:

1. The calendar calculations use the average length of a moon cycle. The actual length of each moon cycle can change a little.
2. The rules for delaying Rosh Hashanah (mentioned above) can sometimes move Rosh Hodesh away from the exact astronomical new moon. The people who created the calendar rules decided that having holidays fall on certain days was more important than having Rosh Hodesh perfectly match the new moon.

Images for kids

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  This Mosaic floor shows a zodiac from a 6th-century synagogue in Beit Alpha, Israel.

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  This drawing from a medieval Hebrew calendar shows items used during the holiday of Sukkot: a palm branch (lulav), myrtle twigs, willow branches, and a citron (etrog).

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  A Jewish calendar, showing the extra month of Adar II.

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  The Trumpeting Place inscription is a stone with Hebrew writing. It is believed to be part of the Second Temple.

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  A bronze Shabbat candlestick holder made in Mandatory Palestine in the 1940s.

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  The Jewish calendar traditionally starts counting years from about one year before the Creation of the world.

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  A shofar is a horn, usually from a ram. It is traditionally blown to mark Rosh Hashanah, the start of the Jewish civic year.

See also

In Spanish: Calendario hebreo para niños