Talk:Axial tilt

message: The Standards section says: "There are two standard methods of specifying tilt", but then it describes only one of them, the one used by IAU. Can anybody figure out what the second standard was supposed to be and (re)insert it? Or, alternatively, remove the phrase about two standards.
82.50.89.222 (talk) 11:13, 27 December 2017 (UTC)
replies: text: One is in relation to the North pole, the other is in relation to the positive pole.  --Lasunncty (talk) 01:30, 29 December 2017 (UTC)
thread_title:  What is the second standard!? 

message: In physical terms any kind of axial tilt of the earth should be called nutation of earth. On the wikipedia-site "nutation" there is just the effect of the moon mentioned. But maybe I'm wrong.   —Preceding unsigned comment added by 131.188.2.11 (talk) 16:09, 24 February 2009 (UTC)
thread_title:  Term axial tilt and nutation, etc... 

message: It is a popular misconception that the sun is at its greatest elevation above the horizon at noon every day. This misconception is reflected in the "Measurement" section: "...the difference of the heights of the Sun above the horizon at noon on the longest and shortest day of the year is twice the obliquity."
Because of the eccentricity of the Earth's orbit around the Sun, the angular velocity of the Earth's orbital motion is not constant. The axial tilt of the Earth also causes a periodic variation in the time that the Sun reaches the meridian. As a result, the Sun may cross the meridian (and reach its maximum height above the horizon) as early as 16 min 33 s before noon (around November 3) or as late as 14 min 6 sec after noon (around February 12). This is explained in detail on the “Equation of time” page.
Of course there is always a tradeoff between maximum scientific accuracy on the one hand and the goal of keeping articles simple and straightforward for non-technical readers on the other hand.
One possibility: “...the difference of the maximum heights of the Sun above the horizon at midday on the longest and shortest day of the year is twice the obliquity.”
The last paragraph of the section would also need to be tweaked similarly.
Piperh 13:15, 29 January 2007 (UTC)
replies: text: It is not that simple. The axis of the moon inclines 1°32' with its orbit around the earth, which on its turn inclines by 5°09'. Therefore the total inclination of the axis with the ecliptic is 6°41' as the two angles always add up due to forced interaction. This was discovered by Cassini in 1721. The information in the moon article is wrong (was wrong, very soon now) --Tauʻolunga 09:25, 4 June 2006 (UTC)
thread_title:  Teleise 

message: Out of curiosity, how is the obliquity quantified? That is to say, what is the instrument by which it may be measured? If an instrument does not exist, what is the mechanism to do so?
— Preceding unsigned comment added by Obhiee (talk • contribs) 17:21, 2006 May 22 (UTC)
:That is a stupid question. But some teachers say that there are no stupid questions, only stupid answers. Well look and decide for yourself; see article. --Tauʻolunga 08:53, 4 June 2006 (UTC)
thread_title:  Query 

message: I am by no means an expert on this subject but some things caught my attention. 
First, we sometimes use degrees minutes and seconds and at other times we use decimal degrees. Should both be used or only one or the other or does it depend? 
Second, early in the article we say that the Earth has an axial tilt of about 23° 27’ and later we say that in 1976 ε equaled 23° 26’ 21.44". We also say that the degree of tilt is diminishing. Is ε the same as the axial tilt? If so, shouldn't the current degree of tilt be smaller than 23° 26’? 
Last, the Tropic of Cancer article says the rate of change is about 0.5" per year but this article does not give a number. --YellowLeftHand 22:59, 26 January 2007 (UTC)
thread_title:  A few odds and ends 

message: The pages detailing the Planets and the Planetoids (asteroids, TNO, dwarf planets) are great.  The authors do great work and I appreciate all the effort and dedication they take.  I do have a suggestion, however.  I believe that we need some additional consistency regarding some items on the tables.  A problem stems from several of the pages using inconsistent relationship reference points for the Inclination, Obliquity, and Ecliptic (earth’s orbital plane) data.  In doing so, the pages need to be brought into some consistent term usage.  For example:
# INCLINATION:  The use of the item for INCLINATION, under the Orbital Characteristics table section (under the various Planet/Planetoid pages), is inconsistent.  Suggestion -- INCLINATION should relate to the body's orbital plane in relation to the Earth's ecliptic (orbital) plane.  If the authors use something else, then they need to specify the "from-and-to" relationship.  Otherwise, the reader is open to confusion, assumption, and the need to check alternative source documents.  Examples of variations-of-use that need to be specified on various Planet/Planetoid pages:  Axial Tilt in relation to the Ecliptic, Body's orbital plane in relation to the Sun's equator, Body's equatorial inclination in relation to the Ecliptic).
# OBLIQUITY:  The use of the items under the Physical Characteristics table section (on the various planet/planetoid pages) is inconsistent, as well.  Some authors use the term:  Axial Tilt.  Others use the term:  Equatorial Inclination.  The ambiguous term, Inclination, is used as well.  Suggestion -- OBLIQUITY should be used, and refer to the Body's equatorial inclination to its own orbital plane around the Host Star.  In the case of satellites and sub-members of binary systems, the relationship can be to the Principal Subsystem Host (instead of the Host Star), but  references to such should be added to the label or to the supporting text.  Im addition, if the author wishes to indicate additional information on the table, that is super -- but doing so should include clarification text 
:Examples:  The Pluto page referencing Pluto's axial tilt in relation to its orbital plane and to the Earth's Ecliptic (an unusual relationship reference for a planet’s axial tilt).  Charon's relationship to Pluto (its principal.  Etc.
At present, several of the Planet and Planetoid (asteroid and TNO pages) use INCLINATION and AXIAL TILT as table items, without clarification as to the relationships (orbital plane, ecliptic, Sun's equator, etc.).  Again, this ambiguity puts the reader in the position of having to go to secondary source documents to verify the intent and accuracy of the page data.
I do not know if this is the page best suited to post these suggestions, but I will copy this under the Inclination and Obliquity sections too.  Tesseract501 7 March 2007
Regarding the given formulae ε = 84,381.448 − 46.84024T − (59 × 10−5)T2 + (1,813 × 10−6)T3, b...
Jean Meeus gives for the 2nd term  -46,8150xT, which however gives a contradictory result (inversion of sign) with the example reckoned with the given Laskar's formulae. Signed: G. Campart, 31 May 2007
— Preceding unsigned comment added by 145.232.254.21 (talk) 13:25, 2007 May 31 (UTC)
The paragraph starting Lower obliquity misuses the term; it perhaps should be Lower obliqueness of radiation, or something like that. --James G. Sack  —Preceding unsigned comment added by Jgsack (talk • contribs) 21:03, 9 November 2008 (UTC)
thread_title:  Terms and Usage for Inclination, Obliquity, and Axial Tilt 

message: I modified the section on glaciation and climatic effects, adapting language from a NOAA site (which is based on papers by Pisias and Imbrie from 1986 and 1987) to render the meaning in a more straightforward way.
Rsed 22:03, 25 August 2007 (UTC)
thread_title: Glaciation

message: the measurement section contained an error in the example saying that an observer at 50 degrees latitude would see the sun at noon on the longest day at 50+23.5 degrees above the horizon which is incorrect, it should be (90-50)+23.5 as 90 minus latitude gives you the altitude of the sun at equinox not just latitude  —Preceding unsigned comment added by 86.155.125.235 (talk) 12:24, 8 September 2007 (UTC)
thread_title:  measurement example 

message: "If we were off that axis by a degree we would burn up or freeze to death."
I'm calling 'baloney' on that statement and removing it. It's not even the least bit scientific.  —Preceding unsigned comment added by Bizzybody (talk • contribs) 13:00, 20 October 2007 (UTC)
thread_title:  Baloney removal 

message: This table uses a thin-space to slightly separate the 3rd and 4th fractional digits of the decimal number 23.439281 .  However, the   (" ") was displaying as a box in my browser.  I changed it to use a unicode construction  (" ").
Axial tilt#Axial_tilt_of_major_celestial_bodies
Since the thin space makes hardly a difference in the display, if the unicode construct doesn't work for everyone, I suggest removing the separator entirely.
KerryVeenstra 17:21, 1 December 2007 (UTC)
replies: text: removed use of Unicode template - defunct & deprecated for (;;) (talk)  08:20, 8 May 2016 (UTC)
thread_title:  Use of thin-space in table 

message: Hi fellow wikipedians!
Due to the fact that this article was tagged with ,
I will scrutinize this article, find cites, do some basic cleanup etc. --Dna-Dennis (talk) 16:30, 25 December 2007 (UTC)
replies: text: I've changed the tag to no footnotes and removed the previous Citations missing tag. The references sections is with references now, but the sources are unclear and its not cited in-text either. Its like some random reference. Venny85 12:39, 6 April 2008 (UTC)
thread_title:  Citing, cleanup and more 

message: It was not clear from reading this article what angles over 90 mean.  Looking at a diagram shown, it appears that the angle is measured opposite to the direction of orbit.  In other words, Earth is tilted away from the direction of orbit, and Venus (over 170 degrees) is tilted towards the direction of orbit.  Being a layperson, a readable clarification of this would be welcome.  —Preceding unsigned comment added by 166.34.158.130 (talk) 19:22, 19 February 2008 (UTC)
replies: text: It's not 177 degrees toward direction of orbit. It's 177 degrees between the perpendicular and the axis of rotation. On its own just saying perpendicular and axis is ambiguous because 177 degrees between these lines at one end is equal to 3 degrees between these lines at the other. So you need to specify which pole of rotation and which pole of perpendicularity you are going to measure from. You do this by using the counter-clockwise pole. Setting zero degrees to be rotation in the same direction as the orbit selects the pole of perpendicularity. Zbayz (talk) 16:25, 25 August 2009 (UTC)
thread_title:  Angles more than 90 degrees 

message: Some user posted confusing text that if the angle between rotational axis and line perpendicular to orbital plane at one end is 177 degree then at other end it is 3 degrees. 
Astronomers specify inner angle. Inner angle of axial tilt is 23.5 which corresponds to outer angle 156.5 but we do not say that axial tilt of earth is 156.5 degrees. Inner angle at both ends is same i.e 23.5 degrees. So I have removed confusing text. Rāmā (talk) 15:49, 17 October 2009 (UTC)
replies: text: right. but do remember that the planet Venus has an axial tilt of 177.3 degrees, which means it spins in the opposite direction. -- 99.233.186.4 (talk) 02:59, 19 November 2009 (UTC)
thread_title:  Axial tilt: 177 degress = 3 degrees 

message: i'm not understanding how this can be unclear. the named context is astronomy, where matters of spin and orbit are fundamental, afaik even to non-experts. perhaps an animation similar to above-referenced external links is best-suited to appear at the top of the page? -- 99.233.186.4 (talk) 02:59, 19 November 2009 (UTC)
thread_title: context tags

message: In today's NASA article Chilean Quake May Have Shortened Earth Days, the following statement is made: "Earth’s figure axis is not the same as its north-south axis; they are offset by about 10 meters (about 33 feet)."
At this moment figure axis and north-south axis give red links. Could someone create redirects to the correct pages on Wikipedia? Wiki-uk (talk) 11:22, 2 March 2010 (UTC)
thread_title:  Missing redirects : 'figure axis' and 'north-south axis' 

message: This statement:
:Tentative evidence has recently emerged for extreme (> 50°) variations in terrestrial axial tilt.
... appears to be a misinterpretation of the researcher's findings and the information in their news release (http://www.princeton.edu/main/news/archive/S15/64/72A37/index.xml?section=newsreleases). Although they hypothesize that the position of the earth's poles may change substantially with relation to the continents, they state explicitly that "the poles themselves would still point in the same direction with respect to the solar system." Thus it is not the orientation of the rotational axis relative to external referents that changes so dramatically, but rather the orientation of the planet and its continents with respect to the rotational axis. The wording of the headline of the news release is rather unfortunate, as it may easily give the wrong impression to someone who does not read the entire text carefully.
Since this hypothesized phenomenon does not involve or affect axial tilt, it would not seem to belong in this article, so it has been removed.
Piperh (talk) 06:31, 12 July 2010 (UTC)
thread_title:  Extreme variations in Earth's axial tilt 

message: Should the angle measures in radians be relative to pi? (that is, instead of 3.10, 0.95pi)? Radians is kinda meant to be used this way. D O N D E groovily Talk to me 03:55, 3 January 2011 (UTC)
thread_title:  Radians units 

message: What is the tilt of the Earth's axis? please please please tell me! i do not have time to read ALL of the info so if someone could post it in the first few paragraphs after answering my question, that would be AMAZIING! thanks, Roza (talk) 00:37, 18 March 2011 (UTC)
thread_title:  HELP! 

message: Removed bullshit article with overdue weight and offtopic on Japan. Precision of measurement could be discussed and that the Japan earthquake(and perhaps other things) was measurable could be mentioned as an aside. (Maybe also mention that they can see weather effects in Earths rotation.)82.169.255.79 (talk) 14:18, 12 April 2011 (UTC)
thread_title:  Removed offtopic stuff about Japan 

message: In the section about "Obliquity of the ecliptic" the text states that the obliquity "is decreasing at a rate of about 47" per century". The term 47" links to the article about Minute of arc, which is reasonable since that is where second of arc is also described. However, when you let your mouse hover over the 47", a tooltip appears saying Minute of arc, which is confusing to the reader since the unit here really is seconds.
Any suggestions on how to solve this?--Oz1cz (talk) 19:45, 30 July 2013 (UTC)
replies: text: We could instead link to "Second of arc" or "arcsecond", which redirect to the "Minute of arc" article. --Lasunncty (talk) 21:26, 3 August 2013 (UTC)
replies: text: Done --Oz1cz (talk) 17:16, 5 August 2013 (UTC)
thread_title:  Minutes and seconds of arc 

message: this is about the tilted axis of the earth it seems to me the axis remain tilted outside of its orbit[ north pole remain tilted away from the sun when the earth is just at the right hand side of the sun, during 22nd December when it is winter in the northern hemisphere]but the images especially the video is showing the difference. if the axis is as it is shown in the video[the moving blue object around the yellow ball] then the it is summer in the northern hemisphere when the earth is at the right or at the eastern side of the sun when it is the month of December as the earth is revolving the sun from west to east. so it seems to me that the diagram needs to be changed.
— Preceding unsigned comment added by 117.241.232.91 (talk) 15:31, 14 October 2013‎ (UTC)
:The right side of the diagram is June, the left is December. The diagram is correct... does the caption need clarification? -Lasunncty (talk) 00:04, 18 October 2013 (UTC)
thread_title:  October 2013 

message: Can somebody add a section, paragraph, or link on theories of how the earth's tilt came about?  — Preceding unsigned comment added by 98.235.167.63 (talk) 01:50, 20 June 2014 (UTC)
thread_title:  Origins of tilt 

message: :clarify|date=January 2013
:I suspect this should be "before", i.e. T is positive for times in the past, and negative for times in the future? the linear term is positive, but above we claim that "it is currently decreasing".
T is the time since the "epoch" J2000.0. It would be exactly opposite this comment - negative before J2000.0, positive after. T is not tilt, it's just a parameter for the equations given here. Tfr000 (talk) 03:33, 7 May 2015 (UTC)
thread_title:  found this clarify tag with comments 

message: I came to this page searching for an expression for the obliquity which would help me to calculate its value during the bronze age (~2000BC).  The equation (attributed to Lascar) is there, but in my view is unusable because of the use of degrees, minutes & seconds.  How on earth is anyone expected to be able to evaluate this expression in this form !?  I have never seen anything so absurd and useless.  What can possibly be in the mind of the person who wrote that ?  Why not quote the expression in the form given here, where the coefficients are in units of seconds of arc:  http://www.neoprogrammics.com/obliquity_of_the_ecliptic/
Or even better, divide by 3600 and express the coefficients in units of degrees with decimal fractions, which is, I suppose, what real people want and use. g4oep  — Preceding unsigned comment added by 77.96.58.212 (talk) 16:58, 20 June 2015 (UTC)
replies: text: Well you have several options... 1) click the link and get the data from Laskar's original paper and put it in whatever form you want, 2)start -> all programs -> accessories -> calculator... 23 degrees = 82800" and 26' = 1560" and the rest is already in seconds, 3)have the computer do those two tedious calculations for you in whatever program you're writing. Tfr000 (talk) 20:35, 21 June 2015 (UTC)

text: The two sources appear to say the same thing. Unfortunately the article failed to provide a correct definition of the time variable for Laskar's equation. I fixed it. Jc3s5h (talk) 14:50, 23 June 2015 (UTC)

text: Fixed. Jc3s5h (talk) 02:03, 24 June 2015 (UTC)
thread_title:  absurd and unusable (and also incorrect) units 

message: Currently, it reads:
 It is the angle between the perpendicular to the plane of the ecliptic (vertical black line) and the planet's rotational north pole (red line).
It used to read:
 Here, a vertical line (black) is drawn perpendicular to the plane of each planet's orbit.
These are not the same, and the current sentence contradicts the article text. I have to go look at some references to remember which is correct. Tfr000 (talk) 14:32, 26 November 2015 (UTC)
replies: text: Fixed it. Tfr000 (talk) 02:36, 16 January 2016 (UTC)
thread_title:  Caption on the first graphic 

message: The article now references , which is about comet Tempel 1, to say that NASA now defines a "positive pole" with the right-hand rule. However, the Planetary fact sheets still have the same old data. We have to pick one. I'd say stick with the planetary fact sheets if we're talking about planets. Maybe make a note that NASA is pretty darn inconsistent! Tfr000 (talk) 00:29, 25 February 2016 (UTC)
replies: text: I removed that particular reference.  The fact sheets now seem to follow the IAU convention, so I have updated the article to reflect this.  --Lasunncty (talk) 07:46, 27 February 2016 (UTC)
thread_title:  NASA data 

message: I have removed two dynamical gif images in the view that they are very distracting when reading the article. The concepts which these images are meant to illustrate are clearly portrayed by the remaining figures and text. I am sure that this will upset the editors who added the gifs so I would be grateful if others could express a view. Peter Mercator (talk) 12:28, 10 June 2016 (UTC)
replies: text: At some level, removing these detracts from an article. Many astronomy concepts are very difficult to explain with still images and text, but very simple with a moving image. I will refrain from expressing my opinion in this case, as one of the images was mine. Tfr000 (talk) 00:59, 4 July 2017 (UTC)
replies: text: I think something like Earth tilt animation.gif could still be useful.  However, I would slow it down a bit or maybe pause at the equinoxes/solstices.  Also, I wondered if there might be a version that shows the continents, but I was surprised that I could not find any other animation of this motion in Commons.  --Lasunncty (talk) 10:07, 4 July 2017 (UTC)
thread_title:  Use of gif images 

message: For comparison of rotation values, would it not be better to use the same unit? I'm unsure if hours or degrees/day would be more appropriate.  — Preceding unsigned comment added by Fcnz (talk • contribs) 11:08, 12 June 2016 (UTC)
thread_title:  Solar System bodies units 

message: Hello fellow Wikipedians,
I have just modified  on Axial tilt. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
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thread_title:  External links modified 

message: I don’t understand this statement. The idea that earth was a sphere first appears in India in early 1st millennium CE. In China it came more than a millennium later than that. ChandlerMinh (talk) 16:24, 2 July 2021 (UTC)
replies: text: Astronomers back then measured the angle between the Sun's noon positions on the solstices.  This did not require knowledge of the shape of the Earth. --Lasunncty (talk) 06:22, 4 July 2021 (UTC)
thread_title:  History 

message: In the article the word "cause" is used 7x. But the cause of the tilt is not explained :-(  — Preceding unsigned comment added by Koitus~nlwiki (talk • contribs) 21:28, 1 October 2021 (UTC)
thread_title:  Cause of the tilt 

message: The page refers to a 41,000 year cycle but the web link it refers to states precession / axial rotation follows a 26,000 year cycle. Are they talking about the same thing? I would amend the page but am not sure… 132.147.119.140 (talk) 03:07, 17 April 2022 (UTC)
replies: text: Right, the precession cycle is 26,000 years, but the change in tilt is not the same as precession.  The article referenced either confuses the two or at least does not make this clear.  41,000 years is the correct period for this particular oscillation.  --Lasunncty (talk) 00:09, 18 April 2022 (UTC)
thread_title:  Precession reference 

message: To reference with what, earth is found tilted? 103.121.172.50 (talk) 14:45, 18 April 2022 (UTC)
replies: text: The line that runs through the north and south poles is not 90° to the plane that contains the Earth's orbit around the Sun, so it is tilted. Another way of saying the same thing is that the plane that contains Earth's equator is not parallel to the plane that contains the Earth's orbit around the Sun. Jc3s5h (talk) 15:34, 18 April 2022 (UTC)
thread_title:  On which/what basis earth is called tilted, to reference to what ? 

message: Is the axis of the Earth tilted to the left or to the right? The two images in the 'Seasons' section are contradictory.--Miguelferig (talk) 12:50, 11 December 2022 (UTC)
replies: text: Both are correct.  They differ in the position of the observer.  --Lasunncty (talk) 10:11, 12 December 2022 (UTC)
thread_title:  Left or right tilt? 

message: of at least the most important connections of this irregularity in the night sky, as understood by human cultures. At least in China, the story about Nüwa doing her best to restore the sky after Gonggong knocked the axis mundi Mount Buzhou off-center is pretty ancient but still very well known. — LlywelynII 06:38, 30 December 2022 (UTC)
thread_title: Could use a popular culture section

message: In the Vietnamese page, the RA for Earth is 0 degree, but in the English page the RA for Earth is undefined. Who's right in here, the Vietnamese page writer, or the English page writer?TheRedsAreMarching1223  10:49, 20 April 2024 (UTC)
replies: text: I looked at the source, and I couldn't find it listed either way.  Maybe I'm just not seeing it, but it actually doesn't matter.  Since the dec is 90°, any value for RA would still point in the same direction. --Lasunncty (talk) 07:30, 30 May 2024 (UTC)
thread_title:  two language have different numbers