Roger Trout, age 11, of Santa Maria, California, for his question:
Why do some months have more days?
Thirty days hath September, April, June and November. All the rest have thirty one except February which has twenty eight and twenty nine days each leap year. That old saying merely makes it easier to figure the number of days in each month, but it fails to explain why some months have more days than others.
Our calendar is a bit clumsy. The months are uneven and have nothing to do with the months of the moon. What's more, the days do not fit neatly into the year. The ancestor of our calendar was devised in ancient days and from time to time people tried to make it more accurate. These corrections account for some of its sloppiness.
Creating a calendar is one of those tasks that looks easy and turns out to be a series of headaches. Basically, of course, it is based on the number of days in the earth's yearly orbit of the sun. More than 6,000 years ago the Egyptians figured that there are 365 days in the year. They devised a calendar with 12 months of 30 days each, plus five extra days at the year's end.
It was ages before they learned that the earth takes about an extra quarter day to complete its orbit. In 238 B.C. they invented the leap year by saving four quarter days and adding an extra whole day at the end of every fourth year. This was perhaps the best early calendar of the Old World. Meantime, the Romans struggled to work out a calendar based on months of different lengths. This was the direct ancestor of our present calendar.
Around 738 B.C., the earliest Roman calendar tried to fit ten lunar months into a year of 304 days. Every second year an extra 22 or 23 days were added and later two more months were added. After 700 years this clumsy, inaccurate calendar had crept three months ahead of the true orbital year.
This is when Julius Caesar consulted astronomers and was told that the real year has 365 1/4 days. So he devised a calendar with 12 months and a leap year. Five of the months were given 30 days, six months got 31 days and poor little February got 29, plus an extra day every fourth year.
Our present calendar inherited these uneven months, with a few changes. For example, it seemed proper to honor Julius Caesar during the 31 day month of July. But later, the Emperor Augustus wanted to be honored with the month of August. However, August was a 30 day month and a Roman Emperor was entitled to nothing but the best. So a day was added and August still has 31 days. The Romans took this calendar day from poor little February, which was left with 28 days and 29 days on each leap year.
Caesar's calendar was not perfect and by 1582 A.D. there was an error of ten days between it and the orbital year. This was adjusted and amore accurate leap year system was devised to give us our present calendar. But the uneven months were left as they were in the ancient days of the Roman Caesars.