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Why is February short?

  1. Sep 25, 2013 #1

    bobie

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    Hi,
    I hope this is the right forum to ask the following:

    January has 31 days, February 28 and March 31 : 90 days in total, is there an astronomical reason why we do not have three 30-day months?
     
    Last edited: Sep 25, 2013
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  3. Sep 25, 2013 #2
  4. Sep 25, 2013 #3

    UltrafastPED

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  5. Sep 25, 2013 #4

    bobie

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    Thanks, excellent explanations!
     
  6. Sep 25, 2013 #5

    tiny-tim

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    also, the year used to begin in march …

    (which is why eg october used to be the eighth, octo-, month)

    so february was the "runt" month that only got what was left over after all the other months had fed o:)
     
  7. Sep 25, 2013 #6

    phinds

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    Cool information. Thanks.
     
  8. Sep 25, 2013 #7

    bobie

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    So, we might have without any problem:
    April through August 31 days and September through March 30 days.
     
  9. Sep 25, 2013 #8
    By February, people were weary of winter. So they shortened February to make spring come sooner. :)
     
    Last edited: Sep 25, 2013
  10. Sep 25, 2013 #9
    That doesn't sound right to me, but I could be wrong. I thought that in the pre-Julian calendar, January, the first of ten months, was named after the god Janus who looked both back and forward to the old and new years. September through December were then months 7 through 10. Afterwards the months of July and August, named after Julius and Augustus Caesar were added, shifting those later months and creating the Julian calendar.
     
    Last edited: Sep 25, 2013
  11. Sep 25, 2013 #10

    tiny-tim

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    from http://en.wikipedia.org/wiki/January#History
    Traditionally, the original Roman calendar consisted of 10 months totaling 304 days, winter being considered a month-less period. Around 713 BC, the semi-mythical successor of Romulus, King Numa Pompilius, is supposed to have added the months of January and February, allowing the calendar to equal a standard lunar year (354 days). Although March was originally the first month in the old Roman Calendar, January became the first month of the calendar year under either Numa or the Decemvirs about 450 BC (Roman writers differ).​
     
  12. Sep 25, 2013 #11
    I sure got that wrong.
     
  13. Sep 26, 2013 #12

    BobG

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    Part right.

    July and August weren't just added to the calendar. Existing months (Quintillus and Sextillus) were renamed in honor of Julius Ceasar and Augustus Ceasar.
     
  14. Sep 26, 2013 #13

    BobG

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    March 21 would have to be on the vernal equinox (or close to it once leap years were set up). December 21 would have to be on the winter solstice (or close, given leap years). Doesn't explain why December, January, and February couldn't all have 30 days, but even in the early days, you wanted the equinoxes and solstices to work out right. That means you can't push days across those key points.

    But you do have to have more short months going from the Autumnal equinox to the Vernal equinox (the Earth reaches perihelion the first week of January) than you do going from the Vernal equinox to the Autumnal equinox (the Earth reaches apihelion the first week of July).
     
  15. Sep 27, 2013 #14

    bobie

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    By how many days is winter shorter than summer?
     
  16. Sep 27, 2013 #15

    D H

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    About five days -- assuming you live in the Northern Hemisphere. It's the other way around if you live in the Southern Hemisphere.
     
  17. Sep 27, 2013 #16

    BobG

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    You could figure that out just by counting the 31 day months between Mar 21 and Sep 21 (Mar, May, July, & Aug) and then counting the 31 day months between Sep 21 and Mar 21 (Oct, Dec & Jan) and then subtracting the days that February is short (2).

    Summer months: +4
    Winter months: +1

    Which comes to a difference of about 5 (at least for really large values of 3).
     
    Last edited: Sep 27, 2013
  18. Sep 27, 2013 #17

    bobie

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    So this solution is viable
     
  19. Sep 27, 2013 #18

    D H

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    It's March 20 and September 22 (on average), not March 21 and September 21.
     
  20. Sep 27, 2013 #19

    Vanadium 50

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    February is so short it is now classified as a "dwarf month".

    I read it on the internet, so it must be true.
     
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