Why did we end up with one 28 day month?

Since it’s February, it seems timely to ask how come this one oddball month is so short. There are roughly 365¼ days in a year. Actually, to be very precise, in the 2,000 epoch a year averages 365.256363004 days, or 365 days 6 hours 9 min 9.76 seconds. That’s how long it currently takes the Earth to complete one full orbit around the Sun, creating our four distinct climactic seasons due to the tilt of the Earth’s axis in relation to our orbital plane around the Sun.

Since quarter days are tough to manage on a calendar, we have a leap year every 4 years, and on leap years we add a whole day to the month of February. And every once in a great deal of years, we still need a special adjustment year that adjusts for the period of time lost each year due to rounding down to 365.25 from the actual 365.256363004 days per year. But none of that explains why February is usually 28 days long and 29 on leap years. Why not have regular years be 7 months of 30 days and 5 of 31. That comes out to 365 days just as our current allocation does. And leap years would just have 6 30-day months plus 6 31-day months, totaling to 366 days No need for an extra short month. Was February a concession to ancient lunar calendars? How did we settle on a single oddball demi-month?