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a simple, but bad, calendar
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The really important thing about our new calendar is that it has to be neat and easy to use. Let’s decide it has 10 months each of 30 days. That’s got to be easier for everyone than remembering which months have 30 days and which have 31, and anyway how many days does February have this year? Our new calendar year will be 300 days long. Great! Now let’s see what happens...
Start the calendar rolling on 1 January 2005, let it roll for a few years and see what happens to the date and the seasons. |
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1 January
A |
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1 January
B
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1 January
C
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Since the Earth actually takes about 365 days to orbit the Sun, look where the Earth is in its orbit every 1 January on your 300 day calendar. |
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Northern hemisphere: |
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Southern hemisphere: |
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By Year C the Earth is the opposite side of its orbit from 1 January Year A ... January 1st is now in the middle of summer in the northern hemisphere. |
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In our simple calendar, January keeps changing seasons - is that a problem? Well yes, because we need the calendar to tell us not only the date, but what time of year it is in terms of the seasons. That's why we try to make the number of days in the calendar year match the number of days in the Earth's orbit as closely as possible. In the end, it seems there really is no alternative to making the numbers of the calendar quite complicated. Sosigenes and Clavius were right after all! |
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