A “calendar history” primer
The idea of creating a calendar began thousands of years ago, when humans first realised the advantages of preparing for the future, such as anticipating annual floods, and of recording the past. But from the beginning it has been an imperfect science of trying to match the lunar cycles (the moon's orbit around the earth), which gives us our months (or moon-ths), with the solar cycle (the earth's trek around the sun), which gives us our year. Although close, the two are not perfectly synchronized.
In ancient Babylonia, around 500 B.C., an extra month was added every two and two-thirds years to even things out. The Egyptians later went with a 365-day year divided into 12 months of 30 days each, adding the extra five days at the end of the year -- which worked out quite nicely until it was discovered that the year is actually closer to 365 1/4 days long. The Romans took a cavalier attitude toward it all, using a 10-month calendar that began in March and ignored the 60 days of winter at the end of their year (and exactly what was wrong with that?).
By 46 B.C. the calendar was a mess. Caesar recruited astronomers to work out a new one, resulting in a 365-day year with months of 30 and 31 days, except February, with 29 days and, every fourth year, 30. The seventh month was renamed July in the emperor's honor. This calendar underwent one small change with the next emperor, Augustus: He renamed the eighth month in honor of himself and stole one of February's days to make his month the same length as Caesar's!
The Julian calendar prevailed for 1,500 years, although it still was not perfect. Every year was 11 minutes and 14 seconds too long, eventually resulting in 10 extra days by the year 1582. Pope Gregory XIII then introduced the civil calendar we follow today, which takes care of the extra 11 minutes or so by eliminating the extra day in leap year centuries that cannot be divided by 400, such as 1700, 1800 and 1900. This calendar is accurate to about 26 seconds of the solar year.
And that, it seems, is about as perfect as it's going to get!
Points for student to ponder
The beginning of a new year is the perfect time to introduce students to the concept of calendars and time-keeping in general. Be sure to teach younger students the "knuckle" method of remembering which months have 30 days and which have 31. (Start with January on the knuckle of your index finger; February is the space between, March is the next knuckle, and so on. The knuckles represent the longer months, the spaces the shorter months.) The origins of the names of our days and months -- an opportunity to introduce ancient mythology! -- will likely be interesting to students of any age. For older students, consider exploring the astronomy that's at the core of our calendar system.
Following are some other ideas for discussion starters and points to ponder. The questions are intended to start children thinking about our calendar and some of the alternatives to it. As students ponder these questions they might consider how they'd like to see the current calendar changed. What would their "perfect calendars" look like?
Imagine cutting 10 whole days from your calendar!
Pope Gregory fixed the too-fast Julian calendar by simply cutting 10 days out of a month. October 4, 1582, was followed by October 15. The new calendar wasn't embraced by all countries. In Great Britain, they waited until 1752 to make the change, and then people furiously protested the loss of what by then was 11 days, citing lost wages and rent collection. At the same time, the colonies in America also made the change -- along with a famous person's birthday! George Washington was born on February 11, according to the Julian calendar, but when the calendar was changed, he changed his birthday to February 22! How would we be affected if we had to institute such a cut today? When would be the best time to do it? What would it be like? Would you change your birthday?
Look into the future
Since the current calendar is off by only 26 seconds each year, that means it will out of step only one day every 3,323 years. The next time this happens will be the year 4905. What will the world be like then? Will calendars still matter? (The extra day, by the way, will be eliminated by dropping the nearest leap day.)
Same time next year -- and the next year, and the next year...
The International World Calendar Association advocates the use of a perennial World Calendar -- a calendar with equal quarters that begins on Sunday, January 1, and remains the same every year through the use of two world holidays, Worlds day at the end of December, and Leap year Day, every four years, at the end of June. This means every day/date pairing would be the same every year, which would allow for easier planning (and would eliminate every-fourth-year "real" birthdays for people born on Feb. 29!). It would also mean that New Year's Eve would always be on a Saturday and Christmas will always be on a Monday. The Fourth of July would always fall on a Wednesday. What day would your birthday fall on? What do you think about your birthday being on the same day for the rest of your life? What would be the pros of this system? What would be the cons? What are the pros and cons of the Gregorian calendar that we use now?
Does our week work?
Where does the week fit into the calendar story? Some people speculate that the seven-day week originates with the four phases of the moon, which take little more than seven days each. Others think it comes from the six days of creation and seventh day of rest described in the Old Testament and first introduced by the Jews as a method of timekeeping. Over time, countries have experimented with variations on the week, such as a 10-day week introduced in France in 1792, and a five-day week (with one day of rest) introduced in the Soviet Union in 1929. What do you think would be the best division? Would you rather have eight days of school and three-day weekends? Or shorter weeks with less of a break? Some adults prefer working 10 hours a day four days a week in order to have a three-day weekend. Would this work out for your family?
Naming the "moon"
The months in the Gregorian calendar are named mostly for gods from ancient myths -- March is named for Mars, for example, the ancient Roman god of war. Native Americans had a different way of naming months, which they called "moons," measured from one new moon to the next. Moons were named for what was happening in the natural world, such as Moon of the Popping Trees, which came at the beginning of the year, when frost made branches crack with cold. Some other names were Moose-Calling Moon, Food-Almost-Gone Moon and Maple-Sugar Moon. To make your own natural calendar, keep notes of what's happening in nature, choose your favorite natural event or the event that seems most representative of the time of year, and name the month after that. (Source: Ranger Rick, March 1997)
Which "animal" are you?
The Chinese lunar calendar is based on the cycles of the moon, with each cycle associated with an animal. People born during a certain cycle are said to have the characteristics of the animal associated with that time. Which "animal" are you? How accurate is the description? Try this lesson plan for exploring the Chinese calendar.
In the sixth century, a monk, Dionysius Exiguus, figured out the year he thought Jesus Christ was born, and called that the year 1. After the date he added the letters A.D., which stood for Anno Domini, or the "year of our lord." All dates before that year are called B.C., or Before Christ. This method of counting is still used for the Gregorian calendar. What if the monk were not Christian? What if he lived at an earlier time? Or a later time? What starting date might he have chosen? The Islamic calendar centers on another important person in the history of religion. Do you know who that is and what event the calendar's starting date is associated with? What if you were to invent your own calendar today? What would the starting date be? According to your speculation, what year would it be now?