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Thread: Topics to cover in a video about the year?

  1. #1
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    Topics to cover in a video about the year?

    I'm thinking of making a video for new years called "What makes the New Year New?" There are a number of topics I think I should raise:

    Difference between the solar day and the stellar day
    Difference between the solar day and the mean solar day
    Difference between the tropical year and the sidereal year
    Shift from lunar to solar calendar
    Adoption of the Julian calendar
    Adoption of the Gregorian calendar
    Adoption of the mechanical clock and the rise of the equal-hour day
    Adoption of midnight as the transition, rather than sunset
    Adoption of Greenwich as the prime meridian and universal time
    Atomic clocks and Universal Coordinated Time
    Adoption and possible abandonment of the leap second

    Are there any obvious ones I'm missing? Also do you know of any good sources I could use? Thanks
    "Occam" is the name of the alien race that will enslave us all eventually. And they've got razors for hands. I don't know if that's true but it seems like the simplest answer."

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  2. #2
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    The fact that the calendar year didn't always start on January 1st.

    Grant Hutchison

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    Oh yeah, that too
    "Occam" is the name of the alien race that will enslave us all eventually. And they've got razors for hands. I don't know if that's true but it seems like the simplest answer."

    Stephen Colbert.

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    Possibly the irregular rate that the length of the day, lunar month, and tropical year are changing.
    Forming opinions as we speak

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    It's probably included within your line of topics, but would ending the video with a look into the past and future of how the length of day changes over time work? As I understand it the length of a day has been getting longer as the Earth's rotation slows down due to moon drag? Not sure how the year length would change unless it also grows longer as the sun burns off mass?

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    I completely misinterpreted the thread title; thinking it would be about Space and Astronomy events in 2019!

    How about Tolkien's Shire Calendar? More sensible than ours, I think.
    Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

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    How about the fact that we demand a "year" be an integer number of Earth rotations relative to the Sun direction, rather than a sidereal orbit? This of course leads to the requirement for leap years. Also, you could get into time zones, and daylight savings time-- those are probably more important to most people than the difference between tropical and sidereal days. And if you really want to get into the nitty gritty, you have the precession of the Earth's axis, such that the leap correction has to include that (it's a year every 26,000 years, so a day every 26,000/365 ~ 712 years.) And if you get into that, you can explain why the choice to make the leap correction such that New Year's day remains in winter, it results in changing the zodiacal constellation that the Sun is in on New Year's eve every 2000 years or so. That last bit might come as a bit of a jolt to common astrology believers.

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    Most astrology believers are already into the "Age of Aquarius" so I don't think that would come as a surprise. Not sure why the difference between the sidereal and tropical years has to be accounted for with a leap year though. Is that just for astronomers?
    "Occam" is the name of the alien race that will enslave us all eventually. And they've got razors for hands. I don't know if that's true but it seems like the simplest answer."

    Stephen Colbert.

  9. #9
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    Quote Originally Posted by parallaxicality View Post
    Most astrology believers are already into the "Age of Aquarius" so I don't think that would come as a surprise. Not sure why the difference between the sidereal and tropical years has to be accounted for with a leap year though. Is that just for astronomers?
    The Gregorian correction is for the difference between the tropical year and 365.25 days. The sidereal year is off by roughly the same amount but in the opposite direction.

  10. #10
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    Quote Originally Posted by parallaxicality View Post
    Most astrology believers are already into the "Age of Aquarius" so I don't think that would come as a surprise.
    I'll bet that most astrology believers who actually know about zodiacal constellations (though I wouldn't be surprised if a lot of them don't know what zodiacal constellations even are) think that the constellation they look up in their horoscope in the newspaper is the constellation the Sun was in when they were born (the so-called "Sun sign"). As for the Age of Acquarius, I'd best most have neve rmade the connection between those two things. For the casual user of astrology, logical consistency is not going to be a strong suit.
    Not sure why the difference between the sidereal and tropical years has to be accounted for with a leap year though. Is that just for astronomers?
    Not just for astronomers, anyone who cares about whether dates refer to astrological signs or to seasons. The decision at some point was made by the powers that be for calendar dates to retain seasonal meanings, not astrological meanings, over thousands of years. Had the choice instead been made to follow astrological beliefs and use a sidereal year (like if the astrology believers cared about consistency), then we'd still have leap days every 4 years, due to the lack of an integer number of Earth rotations. But what I'm talking about is the leap year we need every 712 years or so, due strictly to the axis precession.

    Maybe there are some "serious" astrologers who use the stars rather than the calendar, but I think in most cases people are just making a choice to believe something they like the idea of, so they don't care that it be a system that could actually work over centuries of time. But to highlight the distinction, imagine a society that was so full of astrologically inclined thinkers that they vote to adhere the calendar to the stars rather than to the seasons. Then we'd need to lose something like 6 leap weeks to afix the calendar to the time when the astrological signs were established. Who would like doing that, and who wouldn't? That's how you find out whether people really believe in astrology.-- after all, if the location of the Sun against the stars really helps understand everything that happens and the nature of all the people being born, wouldn't it be worth fixing a calendar to?
    Last edited by Ken G; 2019-Dec-19 at 05:01 PM.

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    Quote Originally Posted by Ken G View Post
    I'll bet that most astrology believers who actually know about zodiacal constellations (though I wouldn't be surprised if a lot of them don't know what zodiacal constellations even are) think that the constellation they look up in their horoscope in the newspaper is the constellation the Sun was in when they were born (the so-called "Sun sign"). As for the Age of Acquarius, I'd best most have neve rmade the connection between those two things. For the casual user of astrology, logical consistency is not going to be a strong suit.
    Not just for astronomers, anyone who cares about whether dates refer to astrological signs or to seasons. The decision at some point was made by the powers that be for calendar dates to retain seasonal meanings, not astrological meanings, over thousands of years. Had the choice instead been made to follow astrological beliefs and use a sidereal year (like if the astrology believers cared about consistency), then we'd still have leap days every 4 years, due to the lack of an integer number of Earth rotations. But what I'm talking about is the leap year we need every 712 years or so, due strictly to the axis precession.

    Maybe there are some "serious" astrologers who use the stars rather than the calendar, but I think in most cases people are just making a choice to believe something they like the idea of, so they don't care that it be a system that could actually work over centuries of time. But to highlight the distinction, imagine a society that was so full of astrologically inclined thinkers that they vote to adhere the calendar to the stars rather than to the seasons. Then we'd need to lose something like 6 leap weeks to afix the calendar to the time when the astrological signs were established. Who would like doing that, and who wouldn't? That's how you find out whether people really believe in astrology.-- after all, if the location of the Sun against the stars really helps understand everything that happens and the nature of all the people being born, wouldn't it be worth fixing a calendar to?
    My bold. I think that should be closer to 71.2 years, as the precession causes a difference of some 20 minutes between the tropical and sidereal years.

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    Good point, my calculation was 26000 /365, for which somehow I got 712 instead of 71.2. So yes, we find out that we care more about how high the Sun is in the sky than what constellation the Sun is in every 71.2 years, not every 712 years, when we include an extra leap day in honor of the former over the latter. Call us self-centered-- weather means more to us than immutable forces that cause everything to happen and people to be the way they are.
    Last edited by Ken G; 2019-Dec-19 at 06:05 PM.

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    Another consideration for that special day might be to note where we are. If you are driving down the road and you see a certain sign or tree or something, you will know how far you are from home or what the time will be when you get there. Similarly, with today's precision astronomy, astrometry can get within perhaps 10 minutes of what time it is just by looking at Barnard's star, for instance. We aren't stuck with a ball sliding down a pole in N.Y. In the past hundreds of years were needed to see things move.

    Referencing the analemma and anything else that sounds like a song title would be another recommendation.
    We know time flies, we just can't see its wings.

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    Quote Originally Posted by Ken G View Post
    Maybe there are some "serious" astrologers who use the stars rather than the calendar, but I think in most cases people are just making a choice to believe something they like the idea of, so they don't care that it be a system that could actually work over centuries of time. But to highlight the distinction, imagine a society that was so full of astrologically inclined thinkers that they vote to adhere the calendar to the stars rather than to the seasons.
    Hi Ken, there is such a society and it is called India. There is a major debate within astrology between the western tropical system which bases signs on the precessing equinoxes and solstices and the Indian Jyotish Vedic system which adheres to the sidereal constellations as the basis for sun signs. Wikipedia Page

  15. #15
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    It is certainly true that Vedic astrology is based on a sidereal rather than tropical system, so they are about 1 sign of the zodiac displaced from what is common in the West (with no noticeable difference in the perceived efficacy of their astrology). But that's not quite what I mean, I'm talking about a society that actually believed in the claims of their own astrology to the point that they would not only wish to have their zodiacal signs properly aligned, but also enough to want the calendar to follow those correctly aiigned signs such that a birth on the date of, say, January 1 always meant the same sign. If astrological signs really had the significance to which they are attributed (completely different personalities, etc.), not only would such a society want to get their sign right, but they might also want the dates to remain consistent with the signs, rather than consistent with the seasons, over timescales of many generations. Right now in the Vedic system, two people born on the same date 72 years apart could be of different astrological sign, because the Sun is in a different zodiacal constellation, which tells us they view it as more important how high the Sun is than what constellation it's in, on that date. In the West, the astrological believer gets to have the Sun be at the same height, and be of the same sign, but not necessarily be in the same constellation.
    Last edited by Ken G; 2019-Dec-31 at 11:22 AM.

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