Category Archives: calendars

do you speak my calendar?

In MacBSD, the command cal 9 1752 shows the shortening of that month in the British Empire. If I reinstall MacOS and choose Italian as its default language, will the shift show up instead in October 1582?

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calendar reform

Each month shall have 30 days, except within a lune spanning 157°15′57″ (5.242199 × 30°) of longitude, wherein the month shall be extended by one day which shall not affect the cycle of the week. The lune so affected shall … Continue reading

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Friday thirteen come on Friday this month

Somewhere or other I recently mentioned having heard that, because the Gregorian calendar cycle of 400 years is a multiple of 7 days, the 13th of the month is not evenly distributed and falls more often on Friday than on … Continue reading

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another thought that I’m never likely to have occasion to apply

If one has the luxury of designing a calendar from scratch, it might be good to put leap day at aphelion, where its angular value is least.

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what could be simpler?

I got yet another wacky idea for a Martian calendar. Start with 24 months of 28 days each. Drop one day from every seventh month (so that a given month is short in one year out of seven), and add … Continue reading

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Martian months

Most proposed calendars for Mars have 24 months, and various systems have been offered to name them. Here’s one more: use the names of the 24 brightest stars, in order of longitude right ascension (relative to the rotation axis of … Continue reading

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to balance a calendar

A Martian year is 668.6 Martian days; that’s 3.4 less than 24×28. I asked myself, how should the short months be arranged for best ‘balance’? I ran all combinations and this is it: The three big dots represent the missing … Continue reading

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