History of the Roman (Julian) Calendar

The Romans were superstitious that even numbers were unlucky, so their months were 29 or 31 days long

Caesar

Related Links

When Rome emerged as a world power, the difficulties of making a calendar were well known, but the Romans complicated their lives because of their superstition that even numbers were unlucky. Hence their months were 29 or 31 days long, with the exception of February, which had 28 days. However, four months of 31 days, seven months of 29 days, and one month of 28 days added up to only 355 days. Therefore the Romans invented an extra month called Mercedonius of 22 or 23 days. It was added every second year.

Even with Mercedonius, the Roman calendar eventually became so far off that Julius Caesar, advised by the astronomer Sosigenes, ordered a sweeping reform. 46 B.C. was made 445 days long by imperial decree, bringing the calendar back in step with the seasons. Then the solar year (with the value of 365 days and 6 hours) was made the basis of the calendar. The months were 30 or 31 days in length, and to take care of the 6 hours, every fourth year was made a 366-day year. Moreover, Caesar decreed the year began with the first of January, not with the vernal equinox in late March.

This calendar was named the Julian calendar, after Julius Caesar, and it continues to be used by Eastern Orthodox churches for holiday calculations to this day. However, despite the correction, the Julian calendar is still 111/2 minutes longer than the actual solar year, and after a number of centuries, even 111/2 minutes adds up.


Did you know?
At its origin, the universe contained only hydrogen and a small amount of helium.

what’s hot

  1. Top 10 End-of-the-Year Gifts for Teachers
  2. 10 Gender-Predicting Old Wives' Tales
  3. Top 10 Backyard Party Games for All Ages
  4. VIEW ALL

highlights

Bug Off! 6 Tick- and Mosquito-Borne Diseases
Which bug bites are dangerous? Learn about 6 diseases spread by ticks and mosquitoes, the signs and symptoms, and treatment options if someone in your family gets infected.

Find Today's Newest & Best Children's Books!
Looking for newly released books for your child? Try our new Book Finder tool to search for new books by age, type, and theme, brought to you by Galactic Hot Dogs.

Top 10 Backyard Party Games for All Ages
Looking for some fun outdoor games for your Fourth of July party or barbecue? Check out these awesome group games, from sack races to cornhole, to make your backyard a kid-friendly party spot!

Registered for Kindergarten — Now What?
Try our award-winning Kindergarten Readiness app! This easy-to-use checklist comes with games and activities to help your child build essential skills for kindergarten. Download the Kindergarten Readiness app today!

stay connected

Sign up for our free email newsletters and receive the latest advice and information on all things parenting.

Enter your email address to sign up or manage your account.

Facebook icon Facebook icon Follow Us on Pinterest

editor’s picks