Why Are the Number of Days in a Month Not Equal?

One answer to this question might be: What difference does it make. This all happened a long time ago. The days of the months are different because they are not equal! But this is only a poor attempt at a joke, of course, and doesn’t explain the complex changes that took place to get us to the modern-day calendar we use now.

First of all, we don’t use the calendar that was common during the Roman era. The calendar used when that empire was at its height changed at least one time in a few decades. The people in charge of making such decisions tried to hold the calendar to the moon’s changes. The time between “new” moons was known to be 29.5 days and that natural activity is the basis for the general length of our months today.

At one time the most accepted calendar was based on 10 months and every month had at least 30 days. Some written histories even show that there was a long period of time that wasn’t part of a month! During the course of a few centuries the majority of people in the world began to measure their lives by the Julian calendar, which had months of 29 days or 30 days.

Though the “official” changes made to calendars, weights and measures etc. were once made by the Roman emperor of the time, the calendar we use today is named for Pope Gregory. He may not have actually made the decision to move to a new calendar but he was Pope at the time that the switch was made from the Julian calendar.

Even the Julian calendar had months with different lengths. When the change was made under Pope Gregory, some months stayed the same, with 31 days. Some months were given an extra day, changing them from 29 days to 30 days. February seems to be the only month that remained the same. Of course, February now has 28 days except for the leap year when one day is added.

Most of the people who have studied the history of our calendar know that the Julian calendar was quite accurate. This means that the Gregorian calendar is also accurate, since a few minor changes were made when Pope Gregory was in office. But there was enough of a discrepancy that the few minutes the Julian calendar was off began to add up. In the late 16th century everyone was “moved ahead” 10 days to get the calendar back on track, so to speak. The leap year adjustment was made at this time as well.

Now we can be sure that the calendar year differs from the true solar year by just a few seconds. It’s interesting to note that some countries around the world didn’t change to the Gregorian calendar for centuries. A few of these nations adopted the modern calendar in only the last 100 years.