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Author Topic:   Why isn't the solstice New Years Day?
dwise1
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Posts: 5930
Joined: 05-02-2006
Member Rating: 5.8


(1)
Message 16 of 33 (714629)
12-24-2013 2:29 PM


Our Calendar is Roman
Julius Caesar established the Julian Calendar in 46 BC (708 AUC, in the 708'th after the founding of Rome). It was a reform of the existing Roman Calendar. The Julian Reform changed the lengths of the months to their current lengths, realigned the calendar to the tropical points (equinoces and solstices), changed the length of the year from 355 to 365 days, set 01 Jan to be the start of the year, and set up the system of leap years every fourth year.
The basis for the Julian leap year system is the length of the tropical year (Winter Solstice to Winter Solstice) being 365.25 days. Thus by adding an extra day every four years, you account for that extra quarter day per year and you keep the calendar aligned with the equinoces that are so important to agriculture. The problem is that the tropical year is actually closer to 365.2425 {ABE: had gotten that switched around; now corrected} days long. As a result, every 400 years we will have added three days too many to the calendar, causing it to drift away from its alignment with the tropical points.
The Gregorian Calendar was a reform that corrected the leap-year rules to eliminate those three extra days every 400 years and to correct for those 1600 years of drift by realigning the calendar to the tropical points once more. Of course, since the Gregorian Calendar was a Catholic thing, the Protestants and Orthodox refused to adopt it, but came to adopt it country by country. The British adopted the Gregorian Calendar in 1752 and the Russians didn't until after the October Revolution in 1918.
The Hebrew Calendar was and still is a lunar calendar with each month starting on the new moon (or is that the Shabbat' associated with the new moon?). It is a very easy calendar system to observe, but it is only very loosely tied to the tropics. For a calendar to be useful for an agricultural society, it needs to track the solstices and equinoces. A solar calendar is much more useful than a lunar calendar, but a solar calendar requires that you have much greater knowledge of astronomy and the facilities to track the sun through the year. The compromise is to constantly realign the lunar calendar to the solar realities. In the Hebrew Calendar, this is done by periodically adding in an entire leap month; some years have an extra month analogous to your extra day every four years.
The Roman Calendar was originally a lunar calendar with only ten months that started at the Spring Equinox. That original Calendar of Romulus was 304 days long with the winter days no belong to any month. 40 years later the Calendar of Numa added Ianuarius and Februarius and had a year that was 355 days long. Februarius was split into two parts between which a leap month, Mensis Intercalaris, would be inserted to bring the calendar back into alignment with the Spring Equinox.
I had always heard, but cannot find that definitive statement, that the Julian Calendar is what took Rome off of a lunar calendar and put it on a solar calendar. And it is the Julian Calendar, as corrected by the Gregorian Calendar, that we continue to use.
However, that does not answer why it is the 21st of the month that the cardinal tropical points take place (ie, Vernal Equinox, Summer Solstice, Autumnal Equinox, Winter Solstice). The only explanation that I have heard was today with Ramoss' reference to when the Roman Senate would first meet after the Winter Solstice, which had marked a season of celebration with the Saturnalia (partying, giving of gifts, seeing the old year out and the new year in -- in medieval times Saturn was depicted as an old man with an hourglass and a crutch and/or a scyth). And of course later during the Empire, the Winter Solstice was set to celebrate Sol Invictus ("Unconquered Sun") in honor of the various sun gods within the Empire. The connection between Christmas and the celebration of Dies Natalis Solis Invicti ("Day of birth of the Unconquered Sun") is obvious, especially considering how early Christianity and early Official Christianity (ie, starting with Constantine) had incorporated so much from the sun god cults of the time, even to the point of replacing the Sabbath with the Day of the Sun (AKA Sunday). Discussion of challenges to this idea are at Sol Invictus and Christianity and Judaism.
Edited by dwise1, : Correcting the length of the tropical year. Sorry about that.

  
Pollux
Member
Posts: 303
Joined: 11-13-2011


Message 17 of 33 (714631)
12-24-2013 2:45 PM


Merry Christmas
Merry Christmas all anyway.
The original Roman calendar started with March. That is why our 9th, 10th, 11th, and 12th months are named after the Latin words for 7, 8, 9, &10 respectively.
If, as Nonukes found, the setting of 25th Dec for Jesus's birth was in the 4th century, the drift of the solstice meant that would probably have been the date for it then.

  
dwise1
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Posts: 5930
Joined: 05-02-2006
Member Rating: 5.8


Message 18 of 33 (714635)
12-24-2013 3:16 PM


Why the 21st?
Regarding the basic question of why the Winter Solstice is officially on the 21st (astronomically, it is when it is, which can vary year to year for various reasons), I found this in the Equinox article (http://en.wikipedia.org/wiki/Equinox#Date):
quote:
Date
When Julius Caesar established his calendar in 45 BC he set 25 March as the spring equinox. Since a Julian year (365.25 days) is slightly longer than an actual year the calendar drifted with respect to the equinox, such that the equinox was occurring on about 21 March in AD 300 and by AD 1500 it had reached 11 March.
This drift induced Pope Gregory XIII to create a modern Gregorian calendar. The Pope wanted to restore the edicts concerning the date of Easter of the Council of Nicaea of AD 325. (Incidentally, the date of Easter itself is fixed by an approximation of lunar cycles used in the Hebraic calendar, but according to the historian Bede the English name "Easter" comes from a pagan celebration by the Germanic tribes of the vernal (spring) equinox.) So the shift in the date of the equinox that occurred between the 4th and the 16th centuries was annulled with the Gregorian calendar, but nothing was done for the first four centuries of the Julian calendar. The days of 29 February of the years AD 100, AD 200, AD 300, and the day created by the irregular application of leap years between the assassination of Caesar and the decree of Augustus re-arranging the calendar in AD 8, remained in effect. This moved the equinox four days earlier than in Caesar's time.

  
Pollux
Member
Posts: 303
Joined: 11-13-2011


Message 19 of 33 (714636)
12-24-2013 3:53 PM


My bad!
dwise1 shows that I went the wrong way in moving the solstice.
I should be more sure of that on which I pontificate!

Replies to this message:
 Message 20 by dwise1, posted 12-24-2013 4:16 PM Pollux has replied

  
dwise1
Member
Posts: 5930
Joined: 05-02-2006
Member Rating: 5.8


Message 20 of 33 (714637)
12-24-2013 4:16 PM
Reply to: Message 19 by Pollux
12-24-2013 3:53 PM


Re: My bad!
Actually, I think we need to work that out, to prove out what the consequences of adding three extra days per 400 year would be. The standard argument is that that had caused the Winter Solstice to have drifted from 21 Dec to 24/25 Dec. Is that so?
I'm going to figure through that right now and will be back shortly. This is an open invitation for others to do the same and to post their findings.

This message is a reply to:
 Message 19 by Pollux, posted 12-24-2013 3:53 PM Pollux has replied

Replies to this message:
 Message 21 by Pollux, posted 12-24-2013 4:52 PM dwise1 has replied
 Message 22 by dwise1, posted 12-24-2013 5:45 PM dwise1 has not replied
 Message 25 by NoNukes, posted 12-25-2013 2:06 AM dwise1 has not replied

  
Pollux
Member
Posts: 303
Joined: 11-13-2011


Message 21 of 33 (714638)
12-24-2013 4:52 PM
Reply to: Message 20 by dwise1
12-24-2013 4:16 PM


Re: My bad!
Nothing wrong with your posting from Wiki. In the 16th century 11 days were dropped from the month of October to bring it back in line. The days of the week were unaffected. The original Julian calendar had about 3 leap years too many every 400 years. With the Gregorian revision I think it is some tens of thousands of years before we will need one more or less leap year to keep things in step. Maybe they should have dropped a couple more days in 16th century to get the solstice back to the 25th!
Not all countries adopted the change at the same time - it was 18th century for England.

This message is a reply to:
 Message 20 by dwise1, posted 12-24-2013 4:16 PM dwise1 has replied

Replies to this message:
 Message 23 by dwise1, posted 12-24-2013 5:47 PM Pollux has seen this message but not replied

  
dwise1
Member
Posts: 5930
Joined: 05-02-2006
Member Rating: 5.8


Message 22 of 33 (714639)
12-24-2013 5:45 PM
Reply to: Message 20 by dwise1
12-24-2013 4:16 PM


Re: My bad!
I started out by setting up the problem in Excel:
quote:
Non-leap year	365
Leap year 366
Total Days Ave Length of year
in 4 years 1461 365.25000
Julian:
in 100 years 36525 365.25000
in 400 years 146100 365.25000
Gregorian:
in 100 years 36524 365.24000
in 400 years 146097 365.24250
Start Date: 21-Dec-2013
400 years later:
Julian 24-Dec-2413
Gregorian 21-Dec-2413

We see that the average year length derived by 400 years according to the Gregorian calendar yields the standard value of 365.2425 days.
For the calculation of the dates, I added the Julian and Gregorian day counts in 400 years. The results suggest support for the idea that the Julian calendar would have caused the drift of the Winter Solstice to ever later dates (eg, from 21 Dec to 25 Dec).
However, since my tool (Excel's date calculations) is based on the Gregorian calendar, I suspect that it may have biased the results.
If we start at 21 Dec and go for 366 days on a leap year, we get this:
quote:
21-Dec	366
to end of Dec 356
January 325
February 296
March 265
April 235
May 204
June 174
July 143
August 112
September 82
October 51
November 21

At the end of November, 21 days are left over, so the full cycle will bring us to 21 Dec.
Now, that was applying the length of a leap year to an actual leap year. Now this is what happens when we apply the length of a leap year to a non-leap year:
quote:
21-Dec	366
to end of Dec 356
January 325
February 297
March 266
April 236
May 205
June 175
July 144
August 113
September 83
October 52
November 22

With 22 days left over, that would place us one day later than it should. This supports the original Excel calculations.
Now I don't completely trust the logic we're following (did I mention that I'm thinking this through as I write this?). What the above shows is that the Julian calendar kept adding an extra day every 100 years, amounting to 3 extra days every 400 years (the 400th year -- eg, 2000 -- is a legitimate leap year). But when that extraneous day is added, an extra day is added to February and so we would not see the date one year later as being different; what we see from that last experiment, making it 366 days instead of 365 as it should be, would not be apparent in the actual operation of the Julian calendar. In effect, we are causing the calendar to run more slowly, in that during that false leap year, we are forcing that year to take longer to transpire.
What is the effect of having a timepiece run more slowly when we are timing something? Consider an event that always takes one minute to transpire. If we time it with a clock that has to run for one minute and ten seconds before it says that a minute has transpired, then we will time that event as having taken less than a minute, namely 51.43 seconds. Therefore, the time at which the event completed will appear to be earlier than it actually was.
From that logic, I would conclude that the effects of the Julian calendar adding more days would have caused the actual astronomical event of the Winter Solstice to have shifted to ever earlier dates; eg, if we start with 21 Dec then after 400 years it would occurred on 18 Dec, after 800 years on 15 Dec, and after 1600 years (about when the Gregorian calendar was devised) on 09 Dec. The shifting of the dates do not work as the standard argument maintains: the Winter Solstice did not shift from 21 Dec to 25 Dec).
But there is an additional wrinkle that I found today at http://en.wikipedia.org/wiki/Equinox#Date and which I had already quoted, but I repeat it now with emphasis added:
quote:
Date
When Julius Caesar established his calendar in 45 BC he set 25 March as the spring equinox. Since a Julian year (365.25 days) is slightly longer than an actual year the calendar drifted with respect to the equinox, such that the equinox was occurring on about 21 March in AD 300 and by AD 1500 it had reached 11 March.
This drift induced Pope Gregory XIII to create a modern Gregorian calendar. The Pope wanted to restore the edicts concerning the date of Easter of the Council of Nicaea of AD 325. (Incidentally, the date of Easter itself is fixed by an approximation of lunar cycles used in the Hebraic calendar, but according to the historian Bede the English name "Easter" comes from a pagan celebration by the Germanic tribes of the vernal (spring) equinox.) So the shift in the date of the equinox that occurred between the 4th and the 16th centuries was annulled with the Gregorian calendar,but nothing was done for the first four centuries of the Julian calendar. The days of 29 February of the years AD 100, AD 200, AD 300, and the day created by the irregular application of leap years between the assassination of Caesar and the decree of Augustus re-arranging the calendar in AD 8, remained in effect. This moved the equinox four days earlier than in Caesar's time.
At the time that the early Christians would have created the tradition of Xmas being on 25 Dec was during that time which was never corrected. In fact, up until the Gregorian Calendar was implemented in 1582, the Vernal Equinox (and hence the Winter Solstice) would have still been observed as being on the 25th. It wouldn't have been until after the Gregorian calendar was adopted by your particular country that it would have shifted "back" to the 21st.
So there is no need to use the Julian calendar's mistake to account for Xmas coinciding with the Winter Solstice.

This message is a reply to:
 Message 20 by dwise1, posted 12-24-2013 4:16 PM dwise1 has not replied

Replies to this message:
 Message 26 by NoNukes, posted 12-25-2013 2:23 AM dwise1 has replied

  
dwise1
Member
Posts: 5930
Joined: 05-02-2006
Member Rating: 5.8


Message 23 of 33 (714640)
12-24-2013 5:47 PM
Reply to: Message 21 by Pollux
12-24-2013 4:52 PM


Re: My bad!
I was in the middle of writing and puzzling through my Message 22 when you responded. I apologize for any talking past each other that may have resulted.

This message is a reply to:
 Message 21 by Pollux, posted 12-24-2013 4:52 PM Pollux has seen this message but not replied

  
frako
Member (Idle past 305 days)
Posts: 2932
From: slovenija
Joined: 09-04-2010


(1)
Message 24 of 33 (714641)
12-24-2013 8:44 PM


We should all adjust our calenders so it fits with a galactic year the time it takes for the earth to go around the galaxy so we are ready when the aliens come
the actual length of the year is 365.242198 days right?

Christianity, One woman's lie about an affair that got seriously out of hand
What are the Christians gonna do to me ..... Forgive me, good luck with that.

  
NoNukes
Inactive Member


Message 25 of 33 (714644)
12-25-2013 2:06 AM
Reply to: Message 20 by dwise1
12-24-2013 4:16 PM


Re: My bad!
Actually, I think we need to work that out, to prove out what the consequences of adding three extra days per 400 year would be. The standard argument is that that had caused the Winter Solstice to have drifted from 21 Dec to 24/25 Dec. Is that so?
I think you are neglecting the ten days that were removed from the calendar when the Gregorian calendar was introduced. I think the answer to your question is that the standard argument is wrong.
As I understand the problem, Christmas was set to December 25th in the 4th century, so the question is whether that Solstice was closer to Christmas around 350 AD.
Here is a rough estimate:
If we backtrack the Solstice from today back to 1582 using the current leap year count, we find that the each year is a tiny bit too long (0.2425 vs 0.24219 days per year). Over (2013-1582)*(0.2425-0.24219) equals 0.13 one day of drift. Since our year is slightly too long on average, that means Solstice back in 1582 was 0.13 days later than now.
Alternatively, and more accurately we can see that we've had 105 leap year days in the 431 years between 1582 and 2013. Without any leap year days, the Solstice would advance over time because our year would be exactly 365 days. 0.24219*431 = 104.4 days earlier by 1582. Adding in the 105 leap years, and there is a net move of 0.6 days later.
To get back to the Julian calendar, we add back the ten days making the Solstice date 9.4 days earlier than today, then we assume a straight leap year every fourth year back tracking to 350 AD.
308 leap years out of 1232 years or exactly 365.25 days per year for the Julian calendar and 365.24219 for the sun. So as we go back in time the date of winter Solstice gets later. 1232 * (0.25-0.2422) = 9.6 days later using the Julian calendar. Adding in the 9.4 days earlier from the Gregorian calendar produces a net offset of about 0.2 days.
By my calculation, the relationship between the winter Solstice and Christmas in 350AD is pretty much the same as it is today.
Of course while I was looking up some of the numbers, I noticed that the Roman Church at some times assumed a date of April 25th for the Vernal Equinox. If they were making astronomical, mistakes like that, then maybe they did think Dec 25th was the winter solstice.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
I believe that a scientist looking at nonscientific problems is just as dumb as the next guy.
Richard P. Feynman
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass

This message is a reply to:
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NoNukes
Inactive Member


Message 26 of 33 (714645)
12-25-2013 2:23 AM
Reply to: Message 22 by dwise1
12-24-2013 5:45 PM


Re: My bad!
In fact, up until the Gregorian Calendar was implemented in 1582, the Vernal Equinox (and hence the Winter Solstice) would have still been observed as being on the 25th.
I think this assumption is really shaky, and likely wrong. For one thing, at the time the Gregorian calendar reform came up, the Winter Solstice had moved to December 11th. The reform corrected it back to December 21st.
Secondly, the date Christmas was set to December 25th was around 350AD and not back in 45 BC. BC???
Edited by NoNukes, : No reason given.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
I believe that a scientist looking at nonscientific problems is just as dumb as the next guy.
Richard P. Feynman
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass

This message is a reply to:
 Message 22 by dwise1, posted 12-24-2013 5:45 PM dwise1 has replied

Replies to this message:
 Message 27 by Pollux, posted 12-25-2013 2:35 AM NoNukes has replied
 Message 29 by dwise1, posted 01-04-2014 5:23 AM NoNukes has replied

  
Pollux
Member
Posts: 303
Joined: 11-13-2011


Message 27 of 33 (714646)
12-25-2013 2:35 AM
Reply to: Message 26 by NoNukes
12-25-2013 2:23 AM


Re: My bad!
The Wikipedia article on the Gregorian calendar states that in the 4th century the solstice was regarded as 21st in the Alexandrian church, and 25th in the Roman, without specifying any reason for the difference. The Alexandrian view eventually prevailed. I haven't checked when it became associated with Jesus's birth.

This message is a reply to:
 Message 26 by NoNukes, posted 12-25-2013 2:23 AM NoNukes has replied

Replies to this message:
 Message 28 by NoNukes, posted 12-25-2013 8:29 AM Pollux has seen this message but not replied

  
NoNukes
Inactive Member


Message 28 of 33 (714650)
12-25-2013 8:29 AM
Reply to: Message 27 by Pollux
12-25-2013 2:35 AM


Re: My bad!
The Wikipedia article on the Gregorian calendar states that in the 4th century the solstice was regarded as 21st in the Alexandrian church, and 25th in the Roman, without specifying any reason for the difference.
The winter solstice is an annually occurring, astronomically determined instant in time. If people using the Gregorian (or Julian) calendar regarded the 25th as the solstice, I would not consider that to be just their view or opinion. They were wrong.
I haven't checked when it became associated with Jesus's birth.
Wikipedia suggests in the 4th century around 350.
Edited by NoNukes, : No reason given.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
I believe that a scientist looking at nonscientific problems is just as dumb as the next guy.
Richard P. Feynman
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass

This message is a reply to:
 Message 27 by Pollux, posted 12-25-2013 2:35 AM Pollux has seen this message but not replied

  
dwise1
Member
Posts: 5930
Joined: 05-02-2006
Member Rating: 5.8


Message 29 of 33 (715341)
01-04-2014 5:23 AM
Reply to: Message 26 by NoNukes
12-25-2013 2:23 AM


Re: My bad!
NoNukes, I am picking your post solely because you mention a date of c. 350 CE when Xmas had been set to 25 December. I would submit that the setting of that date had been based on a relatively long established tradition.
OK, when I had made my statement, I was thinking purely in terms of what the calendar itself said. If everybody just blindly followed what the Julian Calendar, as set down c. 45 BCE by Julius Caesar, said, then they would have blindly insisted that the Winter Solstice fell on 25 Dec. Do please note the blindly (which I had myself not thought of!). In Message 27, Pollux notes:
quote:
The Wikipedia article on the Gregorian calendar states that in the 4th century the solstice was regarded as 21st in the Alexandrian church, and 25th in the Roman, without specifying any reason for the difference. The Alexandrian view eventually prevailed. I haven't checked when it became associated with Jesus's birth.
Please pardon a very slight digression. There is a very epic creationist claim which verges on the legendary that because of the need to add leap seconds to GPS (Global Positioning System, that everybody's smartphone uses all the time),then the earth is slowing down so fast that at the time of its formation it would have been spinning so fast that it would have been a flat pancake. Completely and utter ridiculous! So much so that its apparent originator, Walter Brown, no longer even tries to use it -- in contrast, he still clings to his deliberate rattlesnake protein lie -- http://cre-ev.dwise1.net/bullfrog.html#RATTLESNAKE.
The creationists want to misinterpret leap seconds (every 18 months to a few years, you need to add an extra second to clock time (AKA "Universal Time Coordinated") to keep 12 noon as close as possible to the actual time that the sun passes over the meredian at noon) as meaning that every 18 months or so the earth's rotation has slowed down by one whole second.
That is the complete story of the creationist claim, which is still the current claim of the creationists' favorite "scientist", Kent Hovind. To those creationists I ask, what are "Dr" Hovind's degrees in? Religion, Religious Education, Religious Education. So why would you even begin to imagine that he's any kind of expert in science?
Here is the most common-sense refutation I can think of for that creationist "leap second" hog-wash. Every four years, we add an extra day to the year. Is that supposed to mean that the earth's rotation had slowed down by one whole day in just four years? No, that just means that an actual year (one revolution of the earth around the sun) is not a whole number of days long! OK, so if an entire year is not a whole number of seconds long, then wouldn't it make sense that we would need to add an extra second every once in a while to bring everything back in sync?
Duh????
OK, so we have these fanatical creationists trying to tell us how fast the earth is slowing down. And, yes, it is slowing down because of many factors. OK, so creationists are telling us that the earth is slowing down by 1 second every 18 months. But how fast is it really slowing down.
Well, it turns out that those nasty "atheistic" scientists are doing their "atheistic" best to actually measure these things!!!!!!!!!!
The International Earth Rotation and Reference Systems Service (http://en.wikipedia.org/...ion_and_Reference_Systems_Service) actually does directly and empirically measure the rate at which the earth's rotation is changing. Sometimes it diminishes, but sometimes it increases (eg, when an earthquake causes a portion of the earth's crust to descend). What is known definitively is that the average rate is several thousands of times lower than the creationists' estimates.
OK, I'm back from that digression.
My original statement was based solely on the Julian Calendar which placed the Winter Solstice at 25 Dec. Blind followers of that calendar would have kept the solstice at 25 Dec until the inception of the Gregorian Calendar in 1582. That would have meant that absolutely everybody would have had to looked at the calendar and not at the sky!
In Message 27, Pollux is telling me that the Alexandrians were still looking at the skies!!! Isn't that the very essence of what we are discussing and arguing over here? We have this authoritative source here, Julius Caesar, who's telling us that the Winter Solstice is on 25 December. But here you Alexandrians dare to tell us that you are directly observing the Winter Solstice to be occurring on 21 Dec? Whiskey-Tango-Foxtrot????? (considering that they at that time knew nothing about distilling liquor, knew nothing about dancing in close-embrace, and had absolutely no concept of swing).
Here is my attempt of some kind of a clean-up.
Julius Caesar pronounced 25 Dec as the date of the Winter Solstice. So be it.
So many gods in this Roman Empire are sun gods. In so many of their mythologies, the Winter Solstice plays such an important part. Let us combine them all into one common celebration the Romans thought. As a result, all Sun gods should naturally be considered as having been born at the Roman Winter Solstice, 25 December.

This message is a reply to:
 Message 26 by NoNukes, posted 12-25-2013 2:23 AM NoNukes has replied

Replies to this message:
 Message 30 by NoNukes, posted 01-04-2014 1:13 PM dwise1 has not replied

  
NoNukes
Inactive Member


Message 30 of 33 (715363)
01-04-2014 1:13 PM
Reply to: Message 29 by dwise1
01-04-2014 5:23 AM


Re: My bad!
Julius Caesar pronounced 25 Dec as the date of the Winter Solstice. So be it.
Okay
NoNukes, I am picking your post solely because you mention a date of c. 350 CE when Xmas had been set to 25 December. I would submit that the setting of that date had been based on a relatively long established tradition.
What tradition do you think that was? Celebrating Christmas on the solistice? On December 25th? On the date that other people were celebrating whatever? I think for this particular nit-picky discussion it matters.
OK, so if an entire year is not a whole number of seconds long, then wouldn't it make sense that we would need to add an extra second every once in a while to bring everything back in sync?
Your explanation is not quite right. If the issue were about the length of the year we would handle it using some kind of leap year like scheme.
The issue solved with leap seconds revolves around the mean solar day not being an even number of seconds long as the second is currently defined. A clock day of 24 hours is 86400 seconds, but the average length of a day is 86400.002 seconds long. That 0.002 seconds per day accumulates to about approximately one second over 18 months.
We could define the second to be 1/86400 of a mean solar day. That would be close enough for most purposes, and the leap second problem would disappear.
The problem with redefining the second is that the length of a day also changes over time by something quite a bit smaller than 0.002 seconds per day, so we really don't want to redefine the second based on the earth's rotation. I can remember going 'round and round' on this issue with a creationist.

Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
I believe that a scientist looking at nonscientific problems is just as dumb as the next guy.
Richard P. Feynman
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass

This message is a reply to:
 Message 29 by dwise1, posted 01-04-2014 5:23 AM dwise1 has not replied

Replies to this message:
 Message 31 by Pollux, posted 01-04-2014 3:32 PM NoNukes has not replied

  
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