BS: longest night?

Subject: BS: longest night?
From: clueless don
Date: 22 Dec 05 - 09:48 AM

Having just passed the winter solstice (here in the Northern hemisphere), I think this question is still of interest. I asked it on an astronomy forum, but didn't get any useful answers.

We are taught that the winter solstice is the shortest day of the year (in "mid-Northern latitudes", as Jack Horkheimer would phrase it). But what is the *longest night* of the year? Is it the night from sunset on December 20 to sunrise on December 21? The night from sunset on December 21 to sunrise on December 22? Or some other night altogether?

I have tried a web search to answer this question, but with no luck. The U.S. Naval Observatory site gives sunrise and sunset times, but they are rounded to the nearest minute, which is not precise enough to answer my question.

Anybody know?

Don

Subject: RE: BS: longest night?
From: GUEST
Date: 22 Dec 05 - 11:08 AM

I believe it varies from year to year, but I can't give you a source for this.

Subject: RE: BS: longest night?
From: Jerry Rasmussen
Date: 22 Dec 05 - 11:10 AM

Having taught Astronomy many years ago, I believe that Guest is correct. The shortest day of the year doesn't even always fall on Dec. 21st.

Jerry

Subject: RE: BS: longest night?
From: Ebbie
Date: 22 Dec 05 - 11:11 AM

Good thing that you mentioned your latitude because I would have liked to give you the longest night of the year in northern Alaska.

Subject: RE: BS: longest night?
From: GUEST, Topsie
Date: 22 Dec 05 - 11:13 AM

That Guest was me.

Subject: RE: BS: longest night?
From: clueless don
Date: 22 Dec 05 - 11:17 AM

Yes, Jerry, I realize that in some years the solstice won't be Dec. 21. I was using that as an example for this year (2005.)

I'm somewhat prepared for answers of the form "It depends on this, and it depends on that ...", but I note that many sources state quite confidently that the winter solstice (whichever date it happens to fall on in a given year) is the shortest day of the year. Why the ambiguities as to which is the longest night?

Don

Subject: RE: BS: longest night?
From: TheBigPinkLad
Date: 22 Dec 05 - 11:20 AM

Surely the TWO nights -- either side of solstice -- would be exactly the same length?

Subject: RE: BS: longest night?
From: Bill D
Date: 22 Dec 05 - 11:55 AM

go here

Subject: RE: BS: longest night?
From: Bill D
Date: 22 Dec 05 - 11:59 AM

(got there from here

Subject: RE: BS: longest night?
From: GUEST
Date: 22 Dec 05 - 12:01 PM

If the shortest day, longest night doesn't fall on the same day-night, then what is the real length of our basic year?

Subject: RE: BS: longest night?
From: TheBigPinkLad
Date: 22 Dec 05 - 12:22 PM

Exactly a year.

Subject: RE: BS: longest night?
From: Bill D
Date: 22 Dec 05 - 12:24 PM

The number of days in one revolution of the Earth around the Sun is 365.2422 days

(that 'almost' ¼ extra day is why they have to do leap year every 4 years....and then now & then we have to adjust for the difference netween .2422 and .25 also)

Subject: RE: BS: longest night?
From: MMario
Date: 22 Dec 05 - 12:27 PM

the length of the night on either side of the solstice presumably would flip-flop around just as does the date of the solstice itself.

Subject: RE: BS: longest night?
From: McGrath of Harlow
Date: 22 Dec 05 - 01:43 PM

Well, as Sid Kipper points out, the longest day around here is the day the clocks go back, when there are 25 hours in it, and the shortest day is the day they go forward, when there's only 23 hours.

But clearly the longest night would actually be taking place right now up in the Arctic Circle, where the sun doesn't go down for six months of the year.

Subject: RE: BS: longest night?
From: TheBigPinkLad
Date: 22 Dec 05 - 01:57 PM

the length of the night on either side of the solstice presumably would flip-flop around just as does the date of the solstice itself.

Not sure what you mean by flip-flop (too technical ;o) but taking the moment of solstice as the nadir, the length of darkness immediately before and after would be identical.

Well, as Sid Kipper points out, the longest day around here is the day the clocks go back, when there are 25 hours in it, and the shortest day is the day they go forward, when there's only 23 hours.


But that would be a non-natural day, Kevin. If you flew a jet around the globe you could have a potentially never-ending day. Like the time my Mother in Law stayed for three months.

Subject: RE: BS: longest night?
From: clueless don
Date: 22 Dec 05 - 02:18 PM

Thanks for the link, Bill D, but that site only gives sunrise and sunset times rounded to the nearest minute (just like the Naval Observatory site), which as I said is not precise enough to answer the question.

In response to TheBigPinkLad, the two nights to either side of the solstice *might* happen to be the same length, at least in some particular year, but I don't think it is "surely" the case.

It may depend on the exact time of day that the solstice occurs (as I understand it, we call Dec. 21, 2005 "the winter solstice" because the actual astronomical solstice occured *during* that day.)

Don

Subject: RE: BS: longest night?
From: TheBigPinkLad
Date: 22 Dec 05 - 02:58 PM

Solstice is by definition the point in time that bisects the year. The same temporal distance either way has to be always equal.

Subject: RE: BS: longest night?
From: Peace
Date: 22 Dec 05 - 04:25 PM

Summer.

Winter.

Subject: RE: BS: longest night?
From: JohnInKansas
Date: 22 Dec 05 - 04:48 PM

The critical thing here is the "solstice point" which is the brief instant when the axis of the earth is in the plane defined by the three points 1.) center of the earth, 2.) center of the sun, and 3. a pole of the earth.

Since everything's in motion, the "day" preceding and "day" following, or the night preceding and night following, can be exactly equal only for persons at a longitude that lies in that plane exactly at the instant of the alignment exactly at midnight (or noon), so one day/night is always "just a bit" longer or shorter than the one on the other side of that "instant of alignment" for most of us.

For ritual purposes of frolicking naked in the vinyards it hardly matters if one misses by a day, but to be safe celebrations on the two consecutive nights might be advisable if there's any doubt.

It should also be noted that the 365.2422 days per year refers to the "solar rate" of rotation of the earth, but if you're navigating by precision inertial references it's necessary to use the "sidereal rate" and account for the fact that the earth actually rotates through 366.2422 rotations relative to the galaxy during one 365.3422 day year. Puzzle that one out if you're so inclined.

John

Subject: RE: BS: longest night?
From: JohnInKansas
Date: 22 Dec 05 - 04:51 PM

Pardon typo: NOT "365.3422 day year," BUT "365.2422 day year" in the next to last sentence. Fat Finger Syndrome strikes again.

John

Subject: RE: BS: longest night?
From: Jim Dixon
Date: 22 Dec 05 - 06:21 PM

I think John in Kansas is exactly right. The solstice isn't a day but a moment. Every spot on earth experiences the solstice simultaneously, but according to local time, half the earth experiences it in the a.m. and half in the p.m. If it falls in the a.m., I would expect the night before the day of the 21st (assuming the solstice falls on the 21st) would be the shortest night. If it falls in the p.m., I would expect the night after the day of the 21st would be the shortest night.

Here's another bit of trivia: The latest sunrise and the earliest sunset do*not* occur on the same day. One (I forget which) occurs a few days before the solstice and the other a few days after. I have the vague notion that this is because the earth's orbit around the sun is not circular but elliptical, but I would have a hard time explaining it.

Subject: RE: BS: longest night?
From: TheBigPinkLad
Date: 22 Dec 05 - 06:39 PM

Interesting. I still can't see how it can be possible to bisect a time period with an instant and not have exact halves; however, I've been wrong before (enter chorus). Does anyone know if there is an official point of the solstice [Greenwich, perhaps?]

Subject: RE: BS: longest night?
From: JohnInKansas
Date: 22 Dec 05 - 09:19 PM

BPL -

Agreed, it's a tricky concept. The point is that there's no bisecting of the time period (day before plus day after) except for those points on a longitudinal line where the first day starts exactly twenty four hours before the instant of solstice so that the second "half" of the time can be exactly twenty four hours after the instant. If less than exactly a full day is used up getting to the point where the solstice happens, then part of that same day is spent going away from it. The "following day" spends all it's duration moving away from the point where it happened, so at the end of the second day you're further from the point of maximum solar exposure than at the start of the day before.

See - it's really very simple.

JD -

The eccentricity of the earth's orbit, if I remember ancient studies, is only on the order of about 1 percent (0.01). The orbit really is very nearly a circle. I'm sure with accurate enough instruments one might find an effect of eccentricity, but that's not the main explanation. The difference between when earliest sunrise and latest sunset occur is due, in simplest terms I can think of, to the fact that the length of day is changing during each day and while it's pretty trivial rate/interval calculus, it's nowhere near as simple as for BPL's confusion, to explain this one without drawing pictures and writing equations. And I don't have a curly delta or a swoopy ess sign on my keyboard. (Which makes it easy for me to pretend I might remember how to do it.)

John

Subject: RE: BS: longest night?
From: Bill D
Date: 22 Dec 05 - 11:00 PM

∂ ∫

Subject: RE: BS: longest night?
From: Peace
Date: 22 Dec 05 - 11:05 PM

쳌Ý 쳌ç

Subject: RE: BS: longest night?
From: Peace
Date: 22 Dec 05 - 11:06 PM

CRUD. Why doesn't the copy and paste work?

Subject: RE: BS: longest night?
From: Bill D
Date: 22 Dec 05 - 11:06 PM

I hope those are the ones...

http://www.theworldofstuff.com/characters/.... (I have it saved as a text file, and have it open permanently as part of my Opera wondows...it is a great reference)

Subject: RE: BS: longest night?
From: Peace
Date: 22 Dec 05 - 11:06 PM

쳌Ý 쳌ç

Subject: RE: BS: longest night?
From: Peace
Date: 22 Dec 05 - 11:07 PM

That worked!

Subject: RE: BS: longest night?
From: Bill D
Date: 22 Dec 05 - 11:08 PM

I don't think copy & past works on everything...I had to go to 'view source' to see the code that made those little faces Giok discovered...then I did a search on THAT code and found the page noted.

Subject: RE: BS: longest night?
From: Bill D
Date: 22 Dec 05 - 11:09 PM

(didn't work here)

Subject: RE: BS: longest night?
From: Bill D
Date: 22 Dec 05 - 11:11 PM

try alt 8706 ∂

Subject: RE: BS: longest night?
From: Peace
Date: 22 Dec 05 - 11:11 PM

I was able to copy and paste John's faces, but not your

"Subject: RE: BS: longest night?
From: Bill D - PM
Date: 22 Dec 05 - 11:00 PM

쳌Ý 쳌ç"

Why is that, do you know, Bill?

Subject: RE: BS: longest night?
From: Bill D
Date: 22 Dec 05 - 11:12 PM

I think it's just the lower #s that works...*shrug*

Subject: RE: BS: longest night?
From: Bill D
Date: 22 Dec 05 - 11:14 PM

alt 1 & alt 2 give ☺☻

Subject: RE: BS: longest night?
From: MMario
Date: 23 Dec 05 - 08:56 AM

anyway - THIS year sunrise continues to be later AFTER the solstice until almost the middle of january - then it starts to get earlier, even though sunset does get later so that the days start to increase in lentgth. For my locality the sun will rise as late as 7:42 in the am. That's about 45 minutes AFTER I leave for work.

Subject: RE: BS: longest night?
From: JohnInKansas
Date: 23 Dec 05 - 09:17 AM

None of the symbols tried above display on my browser.

In html, no "figures" are transmitted. The only thing in the file is a character code (a number, either decimal or hex). A font/typeface must be declared if you change fonts to find a special character, and a simple copy and paste doesn't normally inform the page of a change of typeface, so the "character" you paste will be displayed in whatever font is set for the reader's browser. Since the same character number may display a different glyph (picture) in another font, the reader/viewer usually just gets trash. A few "full set" fonts include more symbols and special characters than others, but the special characters generally appear at "high number" character values that will be rendered as "undefined" if the viewer is not using the same font or a similar extended font.

The extended fonts that might include the symbols people have attempted to paste generally must use Unicode character encoding, since the simple ASCII/ANSI character sets simply "don't have enough numbers" to indicate or to display them without changing fonts.

While WinXP theoretically is capable of using Unicode character sets, and Win2K theoretically can be given full Unicode capability, few people have made the changes/selections/settings necessary. Older Windows operating systems can "simulate" using Unicode, but only to a limited extent. Some browsers include limited ability to render a few Unicode extended characters by substituting ASCII/ANSI fonts, but it's difficult to know in advance which ones will work. If you find a way to "paste" an exotic character, only a few of your readers will be able to see it in most cases.

But as I pointed out, although I do know "ways" to post the symbols, I choose to claim the inability of most readers to display them as my excuse for not doing the math.

I presume that those immediately above have chosen to drift the thread into trying to post the symbols as their excuse for not doing the math for themselves.

I'll blow your excuses for evading the real problem by pointing out that you don't really have to do the math to figure out the stated problem for yourselves, if you care to make a few sketches and do a bit of thinking.

For purposes of your "picture analyses" of the earliest sunrise/latest sunset problem, I'll point out the additional hint that the geometry is not symmetrical in or about any plane of reference except at the instant of a solstice or equinox.

John

Subject: RE: BS: longest night?
From: gnu
Date: 23 Dec 05 - 09:17 AM

Wouldn't the longest night be the night Emile Benoit died? Leading to the song "Long Night" by Rawlins Cross? If you like Celtic Rock - even if you don't - check it out. The mix of bodhran, bagpipes, mandolin, guitars and drums will make the hair stand up on your neck. And, the vocals are unusually powerful, in lyrics and in voice.

Hey... gotta plug Maritime Canadian tunes every chance I get, eh? Reel and Roll!

Subject: RE: BS: longest night?
From: GUEST,Art Thieme
Date: 23 Dec 05 - 10:21 AM

The longest night (of what is, definitely, the longest year--waiting for next year to come around), is the one experienced by some fans of the Chicago Cubs basebeall team on the night connected to the day the superb Chicago White Sox won the American's World Series.

;-) Art Thieme

Subject: RE: BS: longest night?
From: Bill D
Date: 23 Dec 05 - 11:41 AM

John...I think that may be the most erudite and oblique way I have ever been chastised....and I'm still not sure exactly what it was for- thread drift, faulty assumptions about display capabilities for symbols, or laziness in math...*wry grin*

Since 'most' folks use PCs and leave the default fonts in place, I assumed that 'most' would see the symbols.

I go now to put on my hair shirt and find some sack cloth & ashes.

Mea culpa, mea culpa. Mea Maxima culpa

Subject: RE: BS: longest night?
From: TheBigPinkLad
Date: 23 Dec 05 - 11:44 AM

Sorry for my absence (I had to sleep). I think we might be talking about two different aspects of the same thing ... but,

if we use as reference the point on the surface of the earth farthest away from the sun at the moment the centre of the earth is farthest away from the sun (i.e. solstice), then

the hours of darkness (night) at that place either side of that moment should be equal, no matter what your longitude, no?

BTW, I appreciate the patience in my enlightenment.

Subject: RE: BS: longest night?
From: TheBigPinkLad
Date: 23 Dec 05 - 12:01 PM

OK, there's already an error in my last post, the earth when farthest away from the sun has nothing to do with solstice, I think I meant when the angle through the poles is at its most oblique ...

Subject: RE: BS: longest night?
From: clueless don
Date: 17 Jan 06 - 11:55 AM

I want to thank everybody for weighing in on this topic. I suspect that JohnInKansas and Jim Dixon (possibly others as well, sorry if I omitted anyone) have identified the main issue, namely that it depends on the exact (local) time at which the solstice occurs. If the solstice occurs between sunset and sunrise, I suspect (may be wrong, I suppose) that the night during which it occurs is the longest night. If the solstice occurs between sunrise and sunset, it gets more complicated. May depend on the before noon/after noon comparison, and that may depend on how you define "noon", i.e. noon on the clock vs. the time at which the sun is at its zenith.

Is it ever possible for the shortest day to be other then the day during which the solstice occurs, I wonder?

Don

Subject: RE: BS: longest night?
From: MMario
Date: 17 Jan 06 - 12:13 PM

well - the shortest day is always different then the day the Summer solstice occurs

Subject: RE: BS: longest night?
From: Mr Red
Date: 17 Jan 06 - 01:21 PM

the way I figure it the latest sunrise is a few days away from the earliest sunset. the longest day is probably halfway twixt.

ditto summer but you have more days to go at and probably more chance that the rotation of the earth makes it non-symmetrical.

but all ya gotta do is subtract the two times and you will find the longest night.

Subject: RE: BS: longest night?
From: Amos
Date: 17 Jan 06 - 01:32 PM

12-21-1980 16:52 12-22-1990 03:07 12-21-2000 13:23
12-21-1981 22:41 12-22-1991 08:56 12-21-2001 19:12
12-22-1982 04:31 12-21-1992 14:47 12-22-2002 01:01
12-22-1983 10:20 12-21-1993 20:36 12-22-2003 06:51
12-21-1984 16:10 12-22-1994 02:25 12-21-2004 12:41
12-21-1985 22:00 12-22-1995 08:14 12-21-2005 18:30
12-22-1986 03:49 12-21-1996 14:05 12-22-2006 00:20
12-22-1987 09:38 12-21-1997 19:54 12-22-2007 06:09
12-21-1988 15:29 12-22-1998 01:43 12-21-2008 11:59
12-21-1989 21:18 12-22-1999 07:32 12-21-2009 17:49

This table shows you the exact time of the winter solstice and its date for various years. Note that the dates cycle between 21 and 22 December and the times are in 24-hour notation.

But it seems obvious that if we have a shortest day in a gradient progression the longest night will be the one just before or the one just after it -- more likely the one before it, since the solstice marks the point where days start growing longer in the cycle. There are only 24 hours in a full day cycle (rounded to the nearest whole hour). ANy time in that cycle not occupied by "day" must be occupied by "night" unless you want to complicate things with nautical twilight, crepuscule, and such middling zones.



A

Subject: RE: BS: longest night?
From: GUEST,Joe_F
Date: 17 Jan 06 - 11:38 PM

It is correct that the latest sunrise & the earliest sunset do not coincide with the winter solstice. In the latitude of Boston, the latest sunrise is 5 January or thereabouts; the earliest sunset, 5 December. There are two reasons for that. The minor one is that the earth's orbit is not quite circular. The major one, I have never understood.

--- Joe Fineman    [e-mail]

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