Roman
Calendar - Why 28 days in February?
We
owe the modern calendar's differing number of days each month to
the Romans. The early Roman calendar consisted of 12 months beginning
in March like this (later January became the start of the year):
| Month |
Length |
| Martius |
31 |
| Aprilis |
29 |
| Maius |
31 |
| Iunius |
29 |
| Quintilis |
31 |
| Sextilis |
29 |
| September |
29 |
| October |
31 |
| November |
29 |
| December |
29 |
| Ianuarius |
29 |
| Februarius |
28 |
| Februarius
(leap years) |
23 |
| Intercalaris
(leap years) |
27/28 |
The
early Romans attempted to syncronize the months with the first crescent
moon following a new moon resulting in some months of 29 days and
some of more.
Every
other year, February was shortened and a leap month (Intercalaris)
was added in an attempt to realign lunar cycles with the solar calendar.
The lengths of the years in a four year cycle of this lunisolar
calendar were 355, 377, 355, and 378 days. This added up to 4 days
too many to stay in sync with the solar year.
Julian
Calendar
Eventually
Julius Caesar asked an astronomer, Sosigenes of Alexandria, Egypt,
to devise a better calendar. What resulted is called the Julian
Calendar. He abandoned aligning the months with lunar cycles, and
adopted months of 30 or 31 days length, keeping February at 28 days.
He introduced an extra day in February in leap years. Sound familiar?
Julius
Caesar re-named the 5th month after himself. His successor, Augustus
Caesar, re-named the 6th month after himself.
The
first day of each month was called Kalendae, or calends. Debts were
due on this day, so books to track payments were called calendarium
(account book) from which we get our modern day calendar.
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