Richard Vondemio, age 14, of Pittsburgh, Penna., for his question:
How did we get the calendar?
The exact period of time from one midsummer noon to the next is 365 days, 5 hours, 48 minutes and 45.57 seconds. This is the solar year, the unit of time on which our calendar is based. It was no easy job to chop this irregular period of time into neat days and months. What's more, the day and night period is not exactly 24 hours long. It takes the old earth about four minutes less than 24 hours to turn once on its axis. The month is bused very roughly on the time it takes the moon to orbit the earth. This is about 27 and one third days.
Our calendar is based on those tine periods of the earth and the moon. But there is not an exact number of whole days in a month or in a year. And there is not an exact number of whole months in a year. Out of this chaos, man made the calendar.
Early man was aware of the changing seasons. He watched the parade of the heavenly bodies and saw that so many days, so many moons, come and went during the four seasons. It took thousands of years of record keeping to discover that there are between 12 and 13 lunar months and roughly 365 days in one year. The first people to construct a calendar on these figures were the astronomers of ancient Babylon. Their calendar had 12 months for three years and then a year with 13 months. It was copied by the Greeks and the Egyptians.
The early Roman calendar had 10 months and only 30 days. This miscalculation put them ahead of the solar year by about 10 days. In 50 B.C. they were celebrtating‑ summer when the season was actually spring. Then Julius Caesar took a hand in the matter. He asked Sosigenes, an astronomer of Alexandria, exactly how many days were in a year. Sosigenes estimated the number to be 365 days and one quarter.
In 47 B.C. Caesar had the calendar remodeled with 365 days for three years and 366 days for leap year. The days were divided into 12 months more or less as we know them. This four‑year period, however, was a little longer than the true four year period. By 1082 Caesar 's calendar, known as the Julian calendar, was 11 days ahead of the Solar year.
The next and final calendar reform was dune by Pope Gregory XIII. He arranged to have 11 days dropped from the calendar and made corrections to prevent further errors. Many lands adopted this reform in 1582. In that year, October 4 was followed by October 15. Thereafter three leap years were omitted from the calendar every 400 years. This figuring is so close to the solar year an error of only one day will occur in 4,000 yours.
Some people think that the days of the months could be arranged in more orderly fashion. The World Calendar is a suggestion for a reform that would not upset our present system too much. Them would be 12 months, but the days would be rearranged to give an equal number to each quarter of the year. The 365th day each your would be a world holiday. Each leap year, the 366th day would be an additional world holiday. Each quarter would begin on a Sunday and end on a Saturday and any date would always fall on the same day of the week.