Talk:Declination

message: The following statement is dubious:
:The Moon also has an annual cycle, with maximum declination at northern hemisphere midwinter and minimum at midsummer.
* This statement is only accurate for the full moon. At other times of the lunar month, the Moon reaches its highest declination at different times of the year.
* The statement should be reworded in a more globally-neutral manner. The full moon would appear highest in the sky closest to the winter solstice and at its lowest closest to the summer solstice - and this statement is true regardless of hemisphere, or which winter or summer solstice is being considered here. From an equatorial perspective, the most northerly full moon is the one closest to the southern solstice, and vice versa. --<SPAN STYLE="font-family:monospace; color:#008800; background-color:#ffffcc; border:1px solid #ff4444;"> B.D.Mills </SPAN> (T, C) 04:19, 19 June 2008 (UTC)
thread_title:  Dubious 

message: *Around Mid-winter, the moon runs the highest when in its waxing gibbous phase, and the lowest when in waning crescent.
*Around the spring equinox, the moon runs the highest when its around first quarter (waxing half-moon), and the lowest when it's around last quarter (waning half moon).
*Around mid-spring, the moon runs the highest when in its waxing crescent phase, and the lowest when in waning gibbous.
*Around the summer solstice, the moon runs the highest when it's around the new moon, and the lowest when around the full moon.
*Around mid-summer, the moon runs the highest when in its waning crescent phase, and the lowest when in waxing gibbous.
*Around the fall equinox, the moon runs the highest when its around last quarter, and the lowest when it's around first quarter. 
*Around mid-fall, the moon runs the highest when in its waning gibbous phase, and the lowest when in waxing crescent.
*Around the winter solstice, the moon runs the highest when it's around the full moon, and the lowest when around the new moon.
There is a bit of variation, regarding the exact points that the moon runs the highest and lowest each time the moon orbits Earth.  This is because the moon's orbit deviates slightly from the ecliptic.  However, since that deviation is less than 1/4 of Earth's axis tilt, Earth's tilt is strongly the dominating factor.  Therefore, the above generalizations are always at least close to actuality.
I'm not sure if there's a word that is used to identify the moon's highest and lowest declinations for each time it orbits Earth.  However, I think that "lunastice" would be a good word, because it replaces the "sol" (Latin for sun) in "solstice" with "luna" (Latin for moon).  I also think that it would be better to use the words "high" and "low", rather than "summer" or "winter", with "lunastice", because the moon's declination, of course, doesn't dictate the seasons like the sun's does.
DKStuntz (talk) 00:45, 7 June 2009 (UTC)
replies: text: Several sources (the Oxford English Dictionary and Ruggles, Astronomy in Prehistoric Britain and Ireland, p. 36) give lunistice, rather than lunastice, for the monthly lunar extremes.  SteveMcCluskey (talk) 15:03, 27 July 2013 (UTC)
thread_title:  When the moon runs the highest and lowest: 

message: "Declination of the Moon is computed by adding Sun's declination (which is called Declination of Place while computing declination of other planets and Moon) to Moon's latitude." 
:It most certainly is not, for 2 reasons. 1) Latitude is measured perpendicular to the ecliptic, while the declination is measured perpendicular to the equator. Thus they cannot simply be added. 2) The Moon may be far from the Sun and thus its declination may be much farther from the Sun's that the latitude difference. Moreover, as I write this 20090807 04:25:57 (UT), the Sun's declination is 16°23 N (of the equator), the Moon's Latitude is 2°24 N (of the ecliptic), and the Moon's declination is 10°05 S (of the equator). There is no simple formula which relates these 3 quantities. You need to know the longitude of the Moon, the obliquity of the ecliptic, and the Moon's latitude in order to determine the Moon's declination. 
:The above is more properly a method for approximating the MAXIMUM declination, or the declination of the Moon's plane rather than the Moon itself. At the moment that the Sun reaches the tropic of Cancer, the equatorial and ecliptic meridian are the same, and thus latitude of the Moon can be added the declination of the Sun. MistySpock (talk) 04:38, 7 August 2009 (UTC)
replies: text: Removed entire section on the Moon, added link to Lunar_standstill MistySpock (talk) 05:25, 23 August 2009 (UTC)
thread_title:  Moon's declination 

message: I'm hoping an astronomer can clarify something I found confusing on this page.  According to the text of the article, declination corresponds to terrestrial latitude; but the accompanying diagram indicates that lines of declination are not parallel, but rather meet at the celestial poles, which would make them longitudinal and not latitudinal.  Is the text wrong, is the diagram wrong, or is there something about the way the earth is projected onto the sky that somehow makes longitude and latitude "switch?"
98.208.141.126 (talk) 06:52, 6 December 2009 (UTC)
replies: text: IANAA. The diagram is showing declination measured along a line through the celestial pole, as terrestrial latitude is angular displacement from the equator measured perpendicular to circles of latitude. The orange text pertains to the orange arrow. The gray arc of celestial longitude is for reference. -Ac44ck (talk) 08:23, 6 December 2009 (UTC)
thread_title:  Declination as latitude 

message: I don't understand what φ (phi) is referring to in this article. What is phi?  —Preceding unsigned comment added by 70.68.138.99 (talk) 05:44, 13 January 2010 (UTC)
thread_title:  What does φ (phi) have to do with anything 

message: I wrote the following article at about the same time as the above computer code. Basically, the article describes how the code was derived, and how it works.
Note that the calculations of the Equation of Time and the Solar Declination are done from first principles. The only data required are the  earth's orbital parameters, the orbital period, eccentricity and the date of perihelion, and the earth's rotational parameters, the rotational period, the tilt of its axis ("obliquity") and the date of the December solstice. No use is made of derivative quantities such as the solar "anomaly".
Despite the unconventional approach and the simplicity of the calculations, they are quite accurate.
Of course, Wikipedia generally hates unconventionality...
DOwenWilliams (talk) 23:02, 31 August 2010 (UTC)
thread_title:  The latitude and longitude of the sun 

message: Both forms are accurate to the precision stated:
*The degrees-minutes value, 23°26', is rounded to the nearest minute.
*The constant in the cosine formula, 23.44, is rounded to the nearest 0.01°.
The axial tilt article cites:
:http://hpiers.obspm.fr/eop-pc/models/constants.html
Where the value is given as:
:23°26'21".4119
This is 23+(26+(21.4119/60))/60 = 23.4392810833°.
The rounded degrees-minutes value, 23°26' = 23.4333°, is slightly less accurate than the decimal value in the cosine formula.
The source cited for the cosine formula uses 23.45. - Ac44ck (talk) 16:54, 10 April 2011 (UTC)
thread_title:  Comparison of decimal and degrees-minutes values for solar declination 

message: The caption for the diagram near the top of the article links "vernal equinox" to the article about the equinox event. Would it be better to link it to http://en.wikipedia.org/wiki/Equinox_(celestial_coordinates) article? 209.131.230.182 (talk) 19:53, 7 May 2013 (UTC)
thread_title:  Link in diagram caption? 

message: Around 2013, someone changed this sentence in the introduction:
 In astronomy, declination (abbreviated dec; symbol δ) is one of the two direction coordinates of a point on the celestial sphere in the equatorial coordinate system, the other being either right ascension or hour angle.
to:
 In astronomy, declination (abbreviated dec; symbol δ) is one of the two direction coordinates of a point on the celestial sphere in the equatorial coordinate system, the other being hour angle.
In fact, hour angle is not used in the equatorial coordinate system, see our own article. This should be changed to right ascension. Tfr000 (talk) 14:04, 11 November 2017 (UTC)
thread_title:  "Hour angle" used incorrectly