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.


Information Please® Database, © 2007 Pearson Education, Inc. All rights reserved.

Did you know?
The 1900 hurricane which hit Galveston, Tex., was deadliest hurricane in the U.S.

what’s hot

  1. Top 10 Classic Board Games for Kids
  2. 10 Gender-Predicting Old Wives' Tales
  3. Top 10 Birthday Gifts for Teenagers (Ages 14-18)
  4. VIEW ALL

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 Twitter icon Follow Us on Pinterest

editor’s picks

highlights

3 Fun Thanksgiving Games for Kids
Looking for some great Thanksgiving games to play with your kids? Print our free Pin the Feathers on the Turkey game, Pin the Hat on the Pilgrim game, and Thanksgiving Parade Bingo game for loads of laughs this Turkey Day!

Kindergarten Readiness App Wins Gold
Our Kindergarten Readiness app won the Gold Award of Excellence in the educational category at the 2014 Communicator Awards. This valuable checklist comes with games and activities to help your child practice the essential skills she needs for kindergarten. Download the Kindergarten Readiness app today!

8 Surprising Sources of Caffeine in Kids' Foods
Even low doses of caffeine can have an effect on your child's health. Since the FDA doesn't require caffeine content on food labels, learn about hidden sources of caffeine in kids' diets.

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, and create reading lists for kids!