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the Analemma

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Nick Thompson

the Analemma

This came up after the service at the mother church, today.

http://www.analemma.com/pages/framespage.html

Being a late riser, and a darkness hater, I regard December 7 (the day after St. Nicholas’s Day, by the way) as the first sign of spring, because it is the day that the afternoons start getting longer. The shortest morning, by the way, appears to occur on January 7, One of 3 days in the year when the sun is at the Zenith at noon. In other words, noon is moving away from sunset faster that the setting sun is moving toward the horizon so the sun starts arriving later on the clock. Or something like that. The way I put it implies two standards of time measurement and I cannot think what the second one is.

I would love to have this explained to me in Defrocked English Major Talk. Also, we have at least one Friammer in the southern hemisphere. Is the same true there, Russ?

Nick

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Robert Holmes-3

Re: the Analemma

As I mentioned, this is the phenomenon that an old colleague of mine would (vainly) attempt to teach me at this time every year. Fortunately we've now got wikipedia, which helps me feel marginally less ignorant.

—R

On Sat, Dec 8, 2018 at 12:33 AM Nick Thompson <[hidden email]> wrote:

This came up after the service at the mother church, today.

http://www.analemma.com/pages/framespage.html

Being a late riser, and a darkness hater, I regard December 7 (the day after St. Nicholas’s Day, by the way) as the first sign of spring, because it is the day that the afternoons start getting longer. The shortest morning, by the way, appears to occur on January 7, One of 3 days in the year when the sun is at the Zenith at noon. In other words, noon is moving away from sunset faster that the setting sun is moving toward the horizon so the sun starts arriving later on the clock. Or something like that. The way I put it implies two standards of time measurement and I cannot think what the second one is.

I would love to have this explained to me in Defrocked English Major Talk. Also, we have at least one Friammer in the southern hemisphere. Is the same true there, Russ?

Nick

Russell Standish-2

Re: the Analemma

In reply to this post by Nick Thompson

I can't say I've noticed, but wouldn't it have to do with where your
city is located within your timezone?

On Sat, Dec 08, 2018 at 12:33:10AM -0700, Nick Thompson wrote:

> This came up after the service at the mother church, today.
>
>
>
> http://www.analemma.com/pages/framespage.html
>
>
>
> Being a late riser, and a darkness hater, I regard December 7 (the day after
> St. Nicholas’s Day, by the way) as the first sign of spring, because it is the
> day that the afternoons start getting longer. The shortest morning, by the
> way, appears to occur on January 7, One of 3 days in the year when the sun is
> at the Zenith at noon. In other words, noon is moving away from sunset faster
> that the setting sun is moving toward the horizon so the sun starts arriving
> later on the clock. Or something like that. The way I put it implies two
> standards of time measurement and I cannot think what the second one is.
>
>
>
> I would love to have this explained to me in Defrocked English Major Talk.
> Also, we have at least one Friammer in the southern hemisphere. Is the same
> true there, Russ?
>
>
>
> Nick
>

> ============================================================
> FRIAM Applied Complexity Group listserv
> Meets Fridays 9a-11:30 at cafe at St. John's College
> to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com
> archives back to 2003: http://friam.471366.n2.nabble.com/
> FRIAM-COMIC http://friam-comic.blogspot.com/ by Dr. Strangelove

--

----------------------------------------------------------------------------
Dr Russell Standish Phone 0425 253119 (mobile)
Principal, High Performance Coders
Visiting Senior Research Fellow [hidden email]
Economics, Kingston University http://www.hpcoders.com.au
----------------------------------------------------------------------------

============================================================
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Meets Fridays 9a-11:30 at cafe at St. John's College
to unsubscribe http://redfish.com/mailman/listinfo/friam_redfish.com
archives back to 2003: http://friam.471366.n2.nabble.com/
FRIAM-COMIC http://friam-comic.blogspot.com/ by Dr. Strangelove

Barry MacKichan

Re: the Analemma

If the earth did not rotate with respect to the stars, each day would be
a year long. The rotation of the earth adds (or subtracts, I’m too
lazy now to figure out which) lots more days. The siderial day (the time
of one rotation wrt the stars) is a few minutes different from the solar
day (the time of one rotation wrt to the sun).

The second point is that the speed of that year-long day varies over the
year. The earth’s orbit is elliptical, so its distance to the sun
varies which means its speed varies (Kepler’s law: the earth sweeps
equal areas in equal times). The variance between the earth’s actual
orbital angular velocity and its average orbital angular velocity
accounts for the variations you cite.

These are not two standards of time measurement, but rather two
different things you can measure with time. The time zones have nothing
to do with it except to determine the 3 days the sun is at the zenith at
noon. (and in fact, if you measure accurately, the probability that the
sun will ever be at the zenith exactly at noon at any given spot on
earth is zero; usually it will happen just before noon on one day and
just after noon on the next, or vice-versa).

--Barry

On 9 Dec 2018, at 19:35, Russell Standish wrote:

> Being a late riser, and a darkness hater, I regard December 7 (the day
> after
>> St. Nicholas’s Day, by the way) as the first sign of spring,
>> because it is the
>> day that the afternoons start getting longer. The shortest morning,
>> by the
>> way, appears to occur on January 7, One of 3 days in the year when
>> the sun is
>> at the Zenith at noon. In other words, noon is moving away from
>> sunset faster
>> that the setting sun is moving toward the horizon so the sun starts
>> arriving
>> later on the clock. Or something like that. The way I put it
>> implies two
>> standards of time measurement and I cannot think what the second one
>> is.