Many Moons Ago
It is easy to see the changes in the appearance of the moon, so early peoples frequently based their calendars on the cycles of the moon. The word “month” comes from the same word as “moon.” Mesopotamia is widely believed to have been the Earth's first civilization. About 3000 years B.C., the Mesopotamians established the city of Sumer in a fertile region between the Tigris and Euphrates Rivers in modern-day Iraq. The Sumerians developed a lunar calendar of 30 day cycles to help them plan their farming. The Babylonians eventually replaced the Mesopotamian civilization, and in 1750 B.C., replaced the old calendar with one of their own. The Babylonian calendar was a lunar one consisting of 12 months made of 29 and 30 days in a cycle. As mentioned earlier, this lunar measuring was not consistent with the solar year; thus it was 11 1/4 days shorter than the 365 1/4 days which comprise a solar year. To make up for this shortfall, seven times in every span of 19 years, the Babylonians added one month. Interestingly, the Babylonians were one of the first to separate the year into weeks of 7 days. They arrived at this because they worshipped the Sun and Moon and five stars they observed not to twinkle. These "stars" were actually the five closest planets: Mercury, Venus, Mars, Jupiter, and Saturn. The Babylonians noticed that the planets moved across the sky through the constellations. Even today, the days of the week are named for the Sun, Moon, and five bright planets, albeit partially from the Germanic nomenclature: Sunday for the Sun, Monday for the Moon, Tuesday for Mars (Tiv in German), Wednesday for Mercury (Woden in German), Thursday for Jupiter (Thor in German), Friday for Venus (Frigg in German), and Saturday for Saturn. Two of the world’s great religions, Judaism and Islam, keep lunar calendars. Most Muslims recognize a 12 lunar month Islamic religious calendar for their private lives, even if they keep a different civil calendar. Originally, each lunar month began when the new moon was first sighted in the evening sky at sunset. Recently, however, many Muslims worldwide recognize official timekeepers in Cairo, Egypt, who announce the beginning of each month. Unlike many other calendars, no attempt is made to keep the Islamic religious calendar synchronized with a solar calendar. So the holy month of Ramadan, a time of prayer and fasting among all Muslims, continually moves through the seasons, occurring about 11 days earlier each solar year. One year, Ramadan might be in the winter, and 16 solar years later, it would be in the summer. The Jewish calendar has 12 or 13 lunar months. The standard year is 12 months, but an extra (or intercalary) month is inserted seven times during a 19-year cycle to keep the religious calendar closely aligned with the solar year. Thus, Jewish religious holidays always occur in the same season, although the exact dates vary. For example, the Jewish holiday Passover is always in spring. The Romans in 753 B.C. developed a calendar based on the solar year. The year began at the vernal (spring) equinox in March (Martius in Latin). Interestingly, the choice of March as the first month of the year is still reflected in our calendar; our names for the months of September, October, November, and December come from the Latin words for seventh, eighth, ninth, and tenth, respectively, reflecting their positions in the Roman year. The year had 305 days made up of 30 and 31 days. Sixty days which were left over had to be interspersed throughout the year. This left 1/4 of a day each year which was not compensated for and so each 120 years, the calendar would be a month late. Later two months were added, Januarius and Februarius and the 12 months were divided into four 31 day and seven 29 day months as well as one 28-day month. This added up to 355 days or 10-1/4 days less than a solar year. Days were added but usually too many so this calendar also proved inaccurate. By 49 B.C., however, the Roman calendar was a full four months off. Julius Caesar ordered the Roman calendar improved. The politicians wanted Januarius to be the first month of the year to coincide with their terms which began in that month. The new calendar was based on a solar year of 365-1/4 days and began with Januarius, to appease the politicians. A Leap Day was to be added in Februarius every fourth year. When the Julian calendar was implemented, ninety days had to be added to resynchronize the calendar. The Julian names for the months are still with us, with the notable exception of August, named for Caesar's successor. The Julian calendar was not perfect, however, nor was it always strictly followed, so errors continued to propagate. By the sixteenth century after Christ, these errors became a problem. There were ten extra days before the vernal equinox. But the Catholic Church was supposed to celebrate Easter on the first Sunday after the first full moon after March 21, the vernal equinox. The Pope, Gregory XIII, ordered modifications to correct the calendar. As a result, October 5, 1582 became October 15, 1582 to eliminate the accumulated 10 extra days. But the calendar required fine tuning as well. The Julian calendar's method of adding a Leap Year every fourth year was not accurate enough. As a result, the Gregorian calendar called for a Leap Year every fourth year (when the year number could be divided by four). Also, the last year in a century (1800, 1900, 2000) had to be able to be divisible by 400 in order to be a leap year. With these changes, it will take about 30,000 years to add only 10 days to the calendar. The Gregorian Calendar has been the dominant calendar in the West ever since. It is universally used in the business world. It was not adopted by Russia until 1918, a year after the Czar fell. Many churches such as the Moslem, Jewish, and Greek Orthodox, still use their own calendars to determine religious observances, however. The state of Israel uses the Hebrew calendar. While China uses the Gregorian Calendar for daily business, it still uses its ancient lunar-solar calendar to calculate holidays such as the Chinese New Year.
Many Moons Ago
Name ____________________ Date ______ Class______ A. Answer the following questions: 1. How many days are in a lunar “year” of 12 lunar months? How many days are in a solar year? 2. Not counting leap years, how many days are in 19 solar years? How many days are in 19 lunar calendar years with an extra month added in seven times? How closely does the Jewish calendar coincide with the solar calendar every 19 years? 3. Why might it be important for farmers and hunters to keep their calendar aligned with the seasons? 4. What kinds of help do calendars provide? What would it be like if there were no calendars? How might this effect people's lives? How would it effect your life? 5. If you examine the calendar carefully, what do you notice about its construction? Does it ever change? What do you think of the way it is organized? Have you ever heard of a different form of calendar? Could the new year start on another day? Could there be more than seven days in the week? B. Invent a New Calendar The Gregorian calendar is probably accurate enough, but might it not be possible to make a calendar which is more convenient? Perhaps each year and each month could start on the same day. Maybe a different number of days per week would allow holidays to fall on the same day each year. 1. Work in your group to plan a new calendar which solves some of the problems in the present one. Be prepared to present your calendar to the class.
2. Discuss what innovations you developed to improve the existing calendar and discuss examples. What would be the reaction of peoples in the world to this new system? What would be the objections? Who would support these changes?