Re: Know your analemma from a hole in the ground
- From: oriel36 <kelleher.gerald@xxxxxxxxx>
- Date: Sat, 8 Nov 2008 12:02:27 -0800 (PST)
On Nov 8, 2:46 am, Dave Typinski <nos...@xxxxxxxxxx> wrote:
Here's a nice clear, concise article from the November issue of
Physics Today on the reason for the existence of astronomical
analemmas.
Oh, and it's free, too.
Sajina, "On ships, trains, and the equation of time", Physics Today
Nov 2008.http://preview.tinyurl.com/5ap3uq
--
Dave
Any reasonably intelligent person will actually enjoy what causes the
daily noon cycles to vary in response to two motions with respect to
the Sun.
The variations in the natural noon cycles are a global event meaning
that hemispherical differences disappear as it refers singularly to
the noon cycle experienced at all points on the planet and the
Equation of Time which represents the difference between natural noon
and clock noon is simply a consequence of the intrinsic global change
in a location with respect to the central Sun as a consequence of
orbital motion and its variation in orbital speed.
The slow orbital change can be seen in Uranus as the rings change
their orientation to the central Sun while daily rotational
orientation remains fixed -
http://hubblesite.org/newscenter/archive/releases/1999/11/video/b
All that is expected from astronomers is to gauge the two 360 degree
motions with respect to the Sun and then grow to admire the orbital
component which does not follow terrestrial longitudes and therefore
causes seasonal variations in daylight/darkness apart from global
variations in the natural noon cycles.
The analemma is a harmless exercise in photographing the Sun using a
24 hour watch (sorry Anthony ! ) but the reasoning behind the
'analemma' is probably the same as Piltdown man to the power of 100
insofar as it introduces the concept of a 'wandering Sun' which would
disgust even the geocentric astronomers -
"Yet [these orbital motions] differ in many ways [from the daily
rotation or first motion]. In the first place, they do not swing
around the same poles as the first motion, but run obliquely through
the zodiac. Secondly, these bodies are not seen moving uniformly in
their orbits, since the sun and moon are observed to be sometimes
slow, at other times faster in their course. Moreover, we see the
other five planets also retrograde at times, and stationary at either
end [of the regression]. And whereas the sun always advances along its
own direct path, they wander in various ways, straying sometimes to
the south and sometimes to the north; that is why they are called
"planets" [wanderers]. Copernicus
The empiricists will swear blind that there is an actual external
reference for constant daily rotation through 360 degrees and give a
specific value for it along with the analemma reasoning,as seen in
that article,but the thrilling gateway to genuine astronomy,as can be
seen in that passage from Copernicus turns the celestial arena into an
adventure that will always repay a thousand times the effort put in to
grasp the premises,methods and insights.
.
- Follow-Ups:
- Re: Know your analemma from a hole in the ground
- From: Curtis Croulet
- Re: Know your analemma from a hole in the ground
- References:
- Know your analemma from a hole in the ground
- From: Dave Typinski
- Know your analemma from a hole in the ground
- Prev by Date: Re: It May Be Cold in 2040
- Next by Date: Re: Know your analemma from a hole in the ground
- Previous by thread: Re: Know your analemma from a hole in the ground
- Next by thread: Re: Know your analemma from a hole in the ground
- Index(es):
Relevant Pages
|
