Why did we end up with one 28 day month?

Asked by ETpro (34605

) February 16th, 2012

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?

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8 Answers

We settled on it because the original calendar only had ten months. When seasons got all out of whack, the then Ceasar (Augustus, aka where the name for August came from) added two months to fix it, and decreed that # of days in all the months. I believe February was one of the months he added, and he decided it was going to have the 28/29 days…. and frankly if you opposed him you’re going to get killed (See Marc Antony).

tedd (14088

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Well, as I understand it, it is for the same reason that “December” (Dec meaning 10) is actually the 12th month and “October” (Oct meaning 8) is actually the 10th month.

Here is the explanation I found on the web:

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Back in the days of Julius Caesar, the months alternated: 31 days, 30 days, 31 days, etc, for a total of 366 days. Then Julius decided he wanted a month named after him. He took the seventh month, named it July, and shoved the rest of the other months a notch down with the last month dropping off the end. That month only had 30 days, but he thought his month should be one of the largest. So he took a day out of February and added it to July, giving July 31 days and February 29.

Then when Augustus came along, he wanted a month as well. He couldn’t be ahead of Julius, so he took the month right after July and named it August. He shoved the other months down as Julius had done, and another one dropped off the end. That month had 31 days. Augustus couldn’t be outdone by Julius on the days, so he took another day out of poor February and added to August. February then had 28 days. We lost 31, and gained 30, for a total now of 365 days.

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So, poor February got shorted two days, we gained two extra months, and October, November, and December got shoved down in the order.

YoBob (12846

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@YoBob That is essentially correct from what I remember, save for only the # of months there were. I know at some point there were only 10, I’m pretty sure that the 11th and 12th months were added at the same time, and I’m fairly sure that Augustus was the one who added them.

tedd (14088

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Thanks guys, I actually learned something from your answers.

john65pennington (29273

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So September used to be the 7th month (Septo).
October used to be the 8th month (Octo)
November use to be the 9th month (Novo)
December use to be the 10th month (Deca)

Thanks to the two Caesars, the names of the last months of the year don’t make sense. Now I see that they stole days from Feb. too!

RocketGuy (15550

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