Talk:Great conjunction

History section
What about adding a great conjunctions in history section to supplement the technical data of the tables? — Preceding unsigned comment added by 83.198.58.105 (talk) 13:01, 2006 August 1 (UTC)

Historical Significance of Great Conjunctions
I agree with the above comment. I am not qualified to do so myself, but it would begin with Albumasar and his influence on western medieval astrology. Then Middelburg and the expectation of the 1484 conjunction. Influence in Germany and in Italy (eg Ficino and the publication of his Plato, and other theories of a religious renovation). Then Lichtenberger's popularisation and blending with Joachimite predictions. Influence on the astrological controversy in Florence during and after Savonarola, especially in relation to GF Pico's publication of Giovanni Pico della Mirandola's anti-astrology text in 1496. The build-up to the 1524 conjunction as related to the build-up to the Peasants' War in German (over 50 publications in 1523) and also the influence on Lutheran Reformation in general (see eg Gustav-Adolf Schoener). The Berndogger (talk) 04:59, 8 September 2008 (UTC)

Added a new section which, I believe, should be the gist of the article: great conjunctions are a fascinating piece of history but for today's astronomy they do not present real interest; so the tables should be moved to a separate page 'List of...' and the historical section should be amended and expanded.Ael 2 (talk) 17:18, 24 September 2011 (UTC)

Triple conjunction 7 BC
The article falsely states that the triple conjunction of Jupiter and Saturn took place in the year 6 BC. This is wrong as can be verified by any astronomical software like "redshift" e.g. This triple conjunction of the two planets is regarded as the Star of Bethlehem by various authors (e.g. Konradin Ferrari d'Occhieppo: Der Stern von Bethlehem in astronomischer Sicht) --Chicygni (talk) 08:02, 7 December 2008 (UTC)

I thought the nearest visible conjunction of Jupiter and Venus was on June 17, 2 B.C., NOT in 7 B.C. - see, for example, The Star that Astonished the World by Ernest L Martin http://en.wikipedia.org/wiki/Ernest_L._Martin Nwpilgrim (talk) 13:44, 25 January 2012 (UTC)nwpilgrim

This was an error arising from misinterpretation of astronomical year numbering (which does not correlate with Gregorian year numbering in BC) - now fixed QuantumPulsar2002 (talk) 19:05, 29 November 2020 (UTC)

Right ascension vs. ecliptical longitude conjunctions
I (and many other 'normal' people) don't know what's the difference..?! 46.114.254.242 (talk) 15:29, 17 February 2011 (UTC)
 * Right ascension is measured along the celestial equator, whereas ecliptic longitude is measured along the ecliptic. The ecliptic is tilted some 23.4° to the equator. This means that ecliptic longitude does not vary linearly with right ascension, although there are four points where it’s the same (when expressed in degrees): 0°, 90°, 180°, and 270°. The conversion formulas are:
 * Where ε is the obliquity of the ecliptic
 * cos λ cos β = cos α cos δ
 * sin λ cos β = sin ε sin δ + sin α cos δ cos ε
 * sin β = cos ε sin δ - sin α cos δ sin ε
 * And the inverse relations are:
 * cos α cos δ = cos λ cos β
 * sin α cos δ = cos ε sin λ cos β - sin ε sin β
 * sin δ = sin ε sin λ cos β + cos ε sin β
 * CielProfond (talk) 02:10, 25 November 2020 (UTC)

Accuracy of long-term predictions
Not that it matters in practice, but I very much doubt that the predicted 7541 occultation can be accepted with any confidence. Even Jupiter and Saturn have too much chaos in their orbits to permit such a calculation. They'll probably be in conjuction, but an occultation would be a matter of pure (and remote) chance. — Preceding unsigned comment added by 2604:2000:7101:6900:EC88:8BAC:73D5:B278 (talk) 14:02, 11 April 2017 (UTC).

Disclaimer now added. QuantumPulsar2002 (talk) 16:17, 10 December 2020 (UTC)

Grand conjunction
"Grand conjunction" redirects here, but according to Chambers 1908 it is not the same thing (Jupiter etc.) but rather one "where several planets or stars are found together". Equinox ◑ 03:19, 24 February 2019 (UTC)

Section move proposal
I propose that section As omens be moved to Conjunction (astrology). This sections are more related to the topic of Conjunction (astrology), as the rest of the article is about great conjunctions as astronomical events, not astrology. QuantumPulsar2002 (talk) 16:15, 10 December 2020 (UTC)
 * Agree –  QuantumPulsar2002 (talk) 16:23, 10 December 2020 (UTC)
 * Agree to the proposal, and maybe add a link to the astrology article in the See Also section. Alexcalamaro (talk) 14:19, 17 December 2020 (UTC)

Astrology section has now been removed (hooray!), after being copy-pasted into astrology conjunction page last week—link to astrology conjunction page now in history section. QuantumPulsar2002 (talk) 15:41, 21 December 2020 (UTC)

expansion suggestions
Astrogeeks, please make this article a bit more accessible by: The calendar is known to have some errors when the year 1 A.D. was determined largely because in those days they: a) didn't use the Gregorian calendar (they used the Roman calendar for hundreds of year after what should have been labeled 1 A.D.) and, b) because the year 1 A.D. was retroactively determined by some monk around 580 or 640 A.D. but contained unknown errors. The most frequent scholarly conclusion is between four and sixteen years, with four being most commonly assumed. So the 6 from this article (or was it 7?) could well the correct value. That makes this year actually 2026! —EncMstr (talk) 07:21, 13 December 2020 (UTC)
 * Wiki-linking astroterminology (like right ascension, ecliptic, closest in notes column) so an educated but ignorant person can figure things out.
 * a photo or diagram of what we can expect to see

Source of the tables listing the Jupiter-Saturn conjunctions between 1800 and 2100?
What is the actual source of the two tables listing the geocentric conjunctions of Jupiter & Saturn between 1800 and 2100? I do not find it mentioned anywhere in the article (perhaps it was mentioned in an earlier version of the article and accidentely got deleted).

Although the times of conjunction are given to the nearest second, those for the conjunction of 21 December 2020 differ several minutes from those computed by the IMCCE (the French Bureau des Longitudes).

According to this online document and their December newsletter the conjunction in right ascension will be at 13h 31m 56s (UTC), the conjunction in ecliptic longitude at 18h 20m 29s (UTC) and the minimum distance will be at 18h 22m 30s (UTC). AstroLynx (talk) 11:11, 16 December 2020 (UTC)

https://sparky.rice.edu/~hartigan/public-night/jupsat2.html is a great source for content or referencing if I don't get to it first
I haven't read much of it yet, I think I'll add some tomorrow. Should I replace the list with the Rice University man's list to at least have some kind of referenced list? The only other original content list I've found is from an astrologer and we are not using that thank you very much. Maybe someone has an offline source with list?Sagittarian Milky Way (talk) 02:20, 18 December 2020 (UTC)

Anyone is welcome to comment as I have made the astrology less long and long-winded than when it was tagged
And moved the original to the suggested article.Sagittarian Milky Way (talk) 17:31, 18 December 2020 (UTC)
 * Looks fine to me. Well done. Alexcalamaro (talk) 08:43, 19 December 2020 (UTC)
 * Yes, thank you very much for your help in sorting out this article—it is much better now. QuantumPulsar2002 (talk) 19:18, 19 December 2020 (UTC)
 * I also thank you. Good job! Jusdafax (talk) 21:08, 20 December 2020 (UTC)

Dates
Is it worth making the dates of the conjunctions a more scientific format; or are these the confirmed dates for a specific location? — Preceding unsigned comment added by 51.9.7.59 (talk) 18:30, 20 December 2020 (UTC)
 * What do you mean? If the PhD in planetary science who published the lists didn't want to use the main scientific standards of Universal Time or Ephemeris Time for some reason he would've mentioned the time zone. If you mean what part of the world these are calculated for they're for the center of the Earth (even though you can't see through rock) which is also the scientific convention for when location isn't mentioned. At any rate location doesn't matter much for making sure the dates of the exact conjunction times are right since (using this conjunction as an example) the planets move 0.2 and 0.1 degrees a day when seen from Earth while geographical location can only make the published positions for time X wrong by up to about 0.0008 and 0.0004 degrees respectively, always in the same direction for a net 0.0004 degrees. (The best time of practical seeing from a specific location can differ from exact time of closest approach by many hours by being noon local time and/or far below the horizon of course) Sagittarian Milky Way (talk) 19:12, 20 December 2020 (UTC)
 * I was thinking at least making the dates consistent - there are a mixture of formats in the article as is. — Preceding unsigned comment added by 51.9.7.59 (talk) 21:12, 20 December 2020 (UTC)
 * Gotcha. Which format? Sagittarian Milky Way (talk) 22:34, 20 December 2020 (UTC)
 * MOS:DATE springs to mind as widely agreed-upon formats. But I guess that leaves a choice of one out of three (the formats without years don't count).  The ISO 8601 format has the advantage of being easily sortable, but I don't know any non-geeks who like it.  —EncMstr (talk) 23:41, 20 December 2020 (UTC)

Semi protection request
Seeing that there have been a number of 'disruptive' edits to this page already today, and that this topic has a lot of attention today, I think making this page temporarily semi-protected for the next few days should be considered. QuantumPulsar2002 (talk) 11:52, 21 December 2020 (UTC)
 * You can request page protection at WP:RFPP, however it appears there have only been two disruptive edits in the past week, which is relatively low – Thjarkur (talk) 12:32, 21 December 2020 (UTC)
 * I agree with Þjarkur, two disputes is relatively low and would not necessarily warrant a temporary semi-protected status. If that changes, it can certainly be addressed. Jurisdicta (talk) 01:07, 24 December 2020 (UTC)

Date Format
Why are the dates formatted as mm/dd/yyyy instead of the widely used dd/mm/yyyy or the ISO yyyy-mm-dd? Churot (talk) 13:18, 21 December 2020 (UTC)
 * Someone addressed your concern soon after you posted. Sagittarian Milky Way (talk) 15:03, 21 December 2020 (UTC)

Good job people who wikified my crappy event lists
I can't automate the simplest thing (besides replace everything exactly matching what's typed in box 1 with box 2) so it would've taken me forever. Sagittarian Milky Way (talk) 17:37, 21 December 2020 (UTC)

A Commons file used on this page or its Wikidata item has been nominated for deletion
The following Wikimedia Commons file used on this page or its Wikidata item has been nominated for deletion: Participate in the deletion discussion at the. —Community Tech bot (talk) 20:32, 23 December 2020 (UTC)
 * Jupiter-and-saturn-conjunction-2020-simulated-view.jpg

1821
What happened to the triple conjunction? Did it happen or not? Surly there must have been witnesses. And it is still shown here. [1821 	Jupiter–Saturn 	June 25 	November 23 	December 23 } []75.155.26.108 (talk) 18:52, 25 December 2020 (UTC)
 * That's right ascension, I checked a software program and in longitude they barely missed crossing again which would require crossing a third time for Jupiter to overtake Saturn 2 decades later making 1821 triple. There is no list in RA anymore because no one could find a source which might make mentioning 1821 without checking all the other events on that list for RA-only triples undue weight and misleadingly complete if another RA-only triple exists. Sagittarian Milky Way (talk) 19:50, 25 December 2020 (UTC)
 * What does that mean in regular English? Did it happen, or not? Some people must think so, or it wouldn't have been mentioned in multiple places. 75.155.26.108 (talk) 01:27, 26 December 2020 (UTC)
 * Picture the 2 places in the world where the 2 planets are overhead: they were on the same longitude 3 different times in 1821 but longitude on the Earth is 23 degrees slanted to longitude in the solar system (this is why Earth has seasons) and they only shared the same longitude once in the longitude of the solar system (there's a slight 1 degree tilt between the longitude in the article which uses Earth's orbit and the rarely used more scientifically accurate longitude of the solar system but that affects things so little compared to the 23 degree thing that even astronomers rarely use the third longitude) Sagittarian Milky Way (talk) 01:31, 26 December 2020 (UTC)

Stitched image?
could you clarify exactly how File:TheGreatConjunction2020.png was created? The figure caption describes this as a "stitched image"? Was this actually multiple images which were composited together? -- RoySmith (talk) 00:24, 26 December 2020 (UTC)

Sorry for the late response, anyhow. Yes, the image in question was created from a merger between 3 stacked images taken by me 4 hours before the closest approach on the Day of the conjunction. I stacked and processed the photos using computer software like PIPP, Registax 6, Autostakkert 3, and then merged 1 wider shot with 2 smaller shots taken using a Barlow lens, to bring out more detail from the Planets and to take a long exposure shot to bring out Titan. I then used Adobe Photoshop to stitch and further process the images, hope I clarified it enough. -- KSPFanatic102 (talk) 18:45, 29 December 2020 (UTC)
 * , Thanks for the reply. This really needs to be disclosed in the image description at c:File:TheGreatConjunction2020.png.  The way things are described now, it appears like this was a single image.  That is, at best, confusing.  If an image like this were submitted as part of a scientific paper to a peer-reviewed journal, leaving out these important details would undoubtedly be grounds for the paper being retracted. -- RoySmith (talk) 19:42, 29 December 2020 (UTC)
 * Thank you, I am a bit inexperienced in editing on Wikipedia so I apologize for any inconvenience, I understand how leaving out those details could cause such issue, so I've went and edited the image description to include the software used to process the Image. I've left out other details as to not confuse the average reader. -- KSPFanatic102 (talk) 19:55, 29 December 2020 (UTC)
 * I've updated the caption; from the description here it's not a stitched image, it's a stacked image. Big difference. Personally I don't think the Commons caption needs to be updated as stacking is something routinely done in astrophotography (the person who doesn't require it for their images is either lying or an absolute legend). Primefac (talk) 17:36, 11 January 2021 (UTC)
 * Yes, it looks better than not dividing the exposure into multiple images. Even Saturn has 100 times less sunlight than Earth photos. Sagittarian Milky Way (talk) 18:05, 11 January 2021 (UTC)

Trigon
I don't see any explanation of "trigon". TomS TDotO (talk) 15:55, 26 December 2020 (UTC)


 * Pentagon is 5 sides, hexagon is 6, octagon is 8 and so on so trigon is jargon for triangle. Sagittarian Milky Way (talk) 16:10, 26 December 2020 (UTC)

Someone needs to fix the triple conjunction diagram
The scorpion is only to the right of the scale in old maps with the planets moving starboard which is how armillary spheres and constellation globes appear from the outside. Sagittarian Milky Way (talk) 01:34, 8 January 2021 (UTC)


 * Based on the work of User:Tomruen at c:Category:Sky trajectories, I've reached out to him to see if he can make a new diagram for us. --Lasunncty (talk) 07:33, 8 January 2021 (UTC)
 * In the mean time, I uploaded a corrected version. From what I could find in astrological charts of 1980-81, Jupiter and Saturn were coming from Virgo into Libra at that time, so Libra was correct, but Scorpius was not.  --Lasunncty (talk) 08:55, 8 January 2021 (UTC)
 * I created an astronomically accurate map. File:Jupiter-Saturn-1981.png Tom Ruen (talk) 09:48, 8 January 2021 (UTC)
 * Great, also I assume not every reader would've known the loops aren't literally parallel like that. Is it possible to draw the planets at all 3 conjunctions and 3 vertical line segments connecting them? Sagittarian Milky Way (talk) 14:22, 8 January 2021 (UTC)