eli5: Why did we design the months in such a way that winter is in January, February and December in a given calendar year?

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Idk if this is a stupid question or not lol. Obviously when moving from one year to the next, January is right in front of December, e.g. December 2023 is right behind January 2024, but is there a reason that months were designed so that winter carries on into the next calendar year?

We have 12 months and 4 seasons, so each season perfectly divides into 3 months a season. With that in mind, why didn’t we design the months so that winter is in 3 consecutive months within the same calendar year?

I’m not sure if I’ve articulated what I mean properly, so let me know if further clarification is needed.

In: Planetary Science

12 Answers

Anonymous 0 Comments

The Romans used to have a calendar with ten months that started in March and ended in December. Then they just had…”Winter”…which was a more vague period that lasted until they were ready for March again.

In time they added two additional months, January and February, although there were *still* different ways of counting how many days were in each month, so they continued to have shorter “Winter” periods before the year started over in March.

The Julian calendar, established by Julius Caesar in 45 BC, firmly established how many days were in each month and moved the start of the year from March to January 1. Most of the months kept their original names, which is why SEPTember and OCTober are now months nine and ten when they sound like they should be seven and eight (because they used to be). Some time after Caesar, the months Quintillus and Sextillus (once months five and six, now seven and eight) were renamed July and August.

The months may once have been aligned with the equinoxes and solstices, but since the length of the year was so strangely variable for such a long time, those fixed points in the earth’s orbit drifted over the calendar toward where they are now. Indeed, that’s why we moved on to the Gregorian calendar…the March equinox was drifting noticeably, making the scheduling of Easter awkward, exposing a long-term flaw in how the Julian calculated leap years. Our current system keeps the equinoxes and solstices in pretty much the same place for many thousands of years. Yes, it would probably make more sense to start the year at one of these points, and we still could (March 21, 2024 could lead into March 22, 2025), but I say that whoever makes that happen has to also go around and change everyone’s computers.

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