Why are there 12 months in the year? Julius Caesar's astronomers explained the need for 12 months in a year and the addition of a leap year to synchronize with the seasons. At the time, there were only ten months in the calendar, while there are just over 12 lunar cycles in a year.
Our lives run on Roman time. Birthdays, wedding anniversaries, and public holidays are regulated by Pope Gregory XIII's Gregorian Calendar, which is itself a modification of Julius Caesar's calendar introduced in 45 B.C. The names of our months are therefore derived from the Roman gods, leaders, festivals, and numbers.