Talk:20000 Varuna

Name
(anonymous) Varuna is an asura, not a deva as this article points.
 * Please quote some refs; editors specialised in mythology will certainly review it. A single statement is not the most helpful way of fixing errors. Eurocommuter 12:14, 15 September 2006 (UTC)

The new 'Picture'
Is an 'artist's conception' really appropriate for a picture? JamesFox 17:18, 17 September 2006 (UTC)


 * If it's a professional space artist, yes. If it's an amateur Wikipedian, no. This looks like the latter; correct me if I'm wrong. The Singing Badger 17:29, 17 September 2006 (UTC)


 * OK. in fact I see it's just a cropped version of the size comparison pic on the same page. Anyone have an opinion on this? The Singing Badger 17:31, 17 September 2006 (UTC)


 * As I have stated on other pages, as long as artist's conception images are duly noted I see no problem with them as they provide some visual concept whether accurate or within reason. Some astronomic objects may never be directly imaged and in those cases an artist's concept may be the best possible guess we may ever have. Abyssoft 02:20, 18 September 2006 (UTC)
 * Well, the problem is that this picture does not illustrate, lack of reference, neither the size, nor colour, nor albedo. In addition, it’s at odds with the elliptic model (see text). The literature presents Varuna (relatively to other KBOs) as reddish, dark, middle-sized, strongly elongated. The picture fails to illustrate any of these characteristics. Consequently, in my opinion, the picture fails to live to the within reason criterion above. Eurocommuter 14:57, 17 March 2007 (UTC)

Size
I may have been premature editing the size of Varuna. My IE 6.0 is not showing the -324 of the previous listed diameter of (text version): 936 (+238/-324). Should we change the diameter to 600 - 1060 km to encompass all the estimates without listing their specific ± margins of error? It looks like Stansberry (2005) has Varuna thermally down to 600±150km with an albedo of 0.21±0.09 Kheider 18:12, 7 November 2006 (UTC)
 * Why do the text and the infobox not agree on the size? Rmhermen (talk) 23:07, 30 December 2007 (UTC)

Actually by KBO standards (given the great distance involved) those estimated diameters of 874km and 936km do match. As the reference shows there have been 4 different thermal estimates for the size of Varuna and the 2 most recent values from 2005 vary a lot. Basically it has a diameter somewhere near the 900km range ±300km. 874km is just the average of the 4 values. -- Kheider (talk) 03:38, 31 December 2007 (UTC)
 * Spitzer diameter estimates are often lower than obtained from other studies. In case of Varuna, the discrepancy is especially significant. Stansberry is inclined to favour earlier (larger) estimates over Spitzer results, quoting quite low signal-noise ratio and the impossibility to fit the beaming parameter for Spitzer observation of Varuna. {The beaming parameter has been introduced to the standard thermal model to account for some hotter than predicted asteroids; it allows for locally higher temperature (the bottom of craters or other rough features); it is arguably difficult to assume/fit and can substantially affect the estimates). Eurocommuter (talk) 16:42, 19 May 2009 (UTC)
 * Ten years down the track and with e.g. the 2013 Herschel observations under our collective belts, this seems to have been revised significantly downwards, more in line with what Spitzer said anyway. Still, my calculation of the possible range of dimensions, including a mean figure, from the estimated range of triaxial proportions, plus the occultation data, is returning a somewhat larger figure for the volumetric mean: $711.1 km$, which is larger than Dysnomia and just a smidge smaller than Varda (perhaps fittingly?). Does that add the smaller estimate extra weight, I wonder, seeing as the error bars of the two figures overlap quite considerably? 146.199.60.87 (talk) 16:34, 11 August 2019 (UTC)
 * Edit: it gets better; if we assume the 2010 treatment of the occultation data is correct, and Varuna (or at least, its primary component, given that the only other positive observation seems to suggest it's a binary / has a moon) is constrained with a larger equatorial axis of about 1003km, a polar axis of about 451km, and a shorter equatorial axis of about 642km (which is not quite in line with the measured light curve, which at "0.4 mag" suggests nothing smaller than 663km, but it's close enough for government work, especially if things like uneven albedo or an elusive, possibly tidally locked mutually-orbiting partner are in play), that gives us an equivalent spheroid diameter of 662km. Never mind squeezing within the error bars of the Spitzer/Herschel data, that's very nearly the same as their best fit estimate. And as the most free dimension of the three is that shorter equatorial diameter, which is a little small for the lightcurve, we can increase that slightly whilst holding the other dimensions static and easily match it bang-on, or at least swing a similar amount the other side of it...
 * Of course, going with conveniently coincidental figures is rather bad science, but given all the different measurements that have been made so far, most of which seem to cling to the regions of either the larger equatorial dimension or this equivalent diameter, it does rather fit the general narrative... 146.199.60.87 (talk) 02:15, 12 August 2019 (UTC)

Mass
Varuna's mass is listed as ~5.9 kg and density of ~1 g/cc, yet that would imply a radius of ~520 km (~1040 km diameter) if spherical shape is assumed. Which is accurate? Dimension or mass? Sethhater123 00:00, 17 January 2007 (UTC)Sethhater123
 * Mass is uncertain by factor several. Diameter 1040 km is within allowed range. Michaelbusch 00:04, 17 January 2007 (UTC)
 * This is another thing I intend to edit, as the estimate seems to mix and match references for diameter and density that may not necessarily correspond. What I've got from my own calculations - using the same source for estimate of density and relative axial dimensions, and the best available estimate for the longest axis (ie the 2010 occultation) - is within the ballpark of the current figure, yet still different enough that it seems prudent to replace it. That is, about 3.316 x 1020kg (with pretty huge error bars, mind - like +1.810/-1.174), vs "~3.7 x 1020kg". Note that this is using an estimated 711.1km volumetric mean diameter (as noted under Size, above), which is itself larger than the currently stated 668km size from the TNOs Are Cool paper; that would work out to just 1.548 x 1020kg... So IDK whether to run with that instead? 146.199.60.87 (talk) 16:27, 11 August 2019 (UTC)
 * Edit: I forgot how to volume. Just cubed the diameter, instead of cubing the radius, then multiplying by 4pi/3. Revised mass estimates are, of course, therefore about 52% of the above figures, as now included on the main page. 146.199.60.87 (talk) 02:06, 12 August 2019 (UTC)

This past event is described in the future tense. Do we have news yet of what emerged?
"Varuna is predicted to occult a magnitude 14.7 star in Gemini on December 7th, 2008. This event will allow at least a lower limit to be placed on Varuna's size. If multiple observers at different locations record the event, several chords across Varuna will be measured, and this will allow the exact size to be measured. Current predictions suggest the event will be visible only from South America and southern Africa."


 * The above text remains in our article. Do we know yet, if people were able to make those measurements, and if so, what the actual results were? -- Cimon Avaro; on a pogostick. (talk) 23:46, 12 January 2009 (UTC)


 * I checked the blog that was cited in the last sentence of that paragraph and updated the article accordingly. Iridia (talk) 05:50, 13 January 2009 (UTC)

Shape
Isn't this almost like Haumea in shape? Lacerda & Jewitt seem to think so. Here's their picture based on light curve data (along side Haumea, aka 2003 EL 61).

I think the picture is grossly misleading, in shape alone. The article text even mentions the shape.

Is this not scientific consensus or something?

68.183.80.244 (talk) 03:32, 3 October 2010 (UTC)


 * I think they believe Varuna is shaped like Haumea (~1400km), but since Varuna is likely less than 800km in diameter, I believe it is below the threshold were they can confirm the shape. -- Kheider (talk) 03:41, 3 October 2010 (UTC)


 * Sounds reasonable. I guess my next question is, if we can't confirm the shape, why are we presenting one? 68.183.80.244 (talk) 04:28, 3 October 2010 (UTC)


 * Under physical characteristics I see the comment "Varuna is thought to be an elongated spheroid (ratio of axis 2:3)" and in the info box we show "(scalene ellipsoid)?". I believe File:Varuna artistic.png may be an old NASA image from before 2002. Sadly I am not sure of the original artistic source. -- Kheider (talk) 04:55, 3 October 2010 (UTC)

Dead link
During several automated bot runs the following external link was found to be unavailable. Please check if the link is in fact down and fix or remove it in that case!


 * http://www.psi.edu/pds/asteroid/EAR_A_COMPIL_3_TNO_CEN_COLOR_V3_0/data/tnocencol.tab
 * In (119070) 2001 KP77 on 2011-05-20 21:17:27, 404 Not Found
 * In 20000 Varuna on 2011-05-25 06:57:38, 404 Not Found
 * In (119070) 2001 KP77 on 2011-05-31 04:11:44, 404 Not Found
 * In 20000 Varuna on 2011-06-10 04:57:16, 404 Not Found

--JeffGBot (talk) 04:57, 10 June 2011 (UTC)

Dead link 2
During several automated bot runs the following external link was found to be unavailable. Please check if the link is in fact down and fix or remove it in that case!


 * http://www.ifa.hawaii.edu/~jewitt/papers/VARUNA/JAE2001.pdf
 * In 20000 Varuna on 2011-05-25 06:57:38, 404 Not Found
 * In 20000 Varuna on 2011-06-10 04:57:25, 404 Not Found

--JeffGBot (talk) 04:57, 10 June 2011 (UTC)

Name 2
What led the IAU to giving the special number 20000 to this object? --129.13.72.196 (talk) 08:10, 9 September 2015 (UTC)
 * It's in the article. Basically, at the time it was considered special. --JorisvS (talk) 10:29, 9 September 2015 (UTC)
 * They knew it would be a relatively large object, especially for something discovered in 2000. -- Kheider (talk) 19:07, 9 September 2015 (UTC)

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TNOs Are Cool reference
OK, bear with me on this one. I deleted it and replaced with Citation Neededs because the clickable arXiv link doesn't contain any reference to Varuna at all ... but when I reopened the PDF directly from its URL in the pagecode (just before wiping it - though I didn't read it until afterwards - because I wanted to refer back to it to double check whether the data belonged to a different object), it opened an entirely different paper that is flush with usable references - yet with the same general title?!

Obviously something weird is going on, maybe at the arXiv end. I'm going to try and repair it and, if the data matches, replace the incorrect URL with the correct one. It's just probably going to involve some edit reversion and so-on, so, it may take a little while and look suspicious whilst I'm in the middle of it. 146.199.60.87 (talk) 16:22, 11 August 2019 (UTC)


 * Edit: looks like whoever committed that link originally didn't realise the paper was in multiple parts, and just committed whatever reference they first found for it on arXiv (which seems to be a very popular one amongst the TNO articles, as it covers a lot of the larger objects - just not Varuna itself) as the "correct" one without double checking. Actually, the correct part isn't on arXiv for some reason, but it is available elsewhere, including on the Internet Archive, which is the link I've added... along with a secondary link to the ADS, because the old one arrived at via the Bibcode is at great pains to warn us that the old site is shutting down in a couple of months. 146.199.60.87 (talk) 21:54, 11 August 2019 (UTC)

2010 Occultation result
Does anyone know what the full result from this bit of measurement was? I can only find an abstract for the 42nd DPS meeting, there are some places offering fulltext and the DPS site itself pretends to offer videos from the conference (but not any online accessible version of the bulletin, even though it went wholly online just one year later), but all of those links hit brick walls of inaccessibility. The fact that it says the negative result from an observatory near to the one positive measurement (out of like 11!) constrains the shape to be long and thin suggests that it places a certain upper bound on the shorter axis of Varuna's shadow, but the abstract doesn't say what that might be. Nor, without knowing what the actual chord length was or how it is thought to be located relative to the centre point and outer edges of the shadow, can we figure it out for ourselves... unless anyone knows a way to convert distance between observatories to width of occulting object without knowing that? (And, well... in general, it's not something as simple as "the shadow is the same size as the object itself, because the star being occluded is relatively so far away as to be effectively at infinity", is it? If so, and we could figure the speed at which the shadow moved across the face of the Earth, then the actual chord length could be recovered from the period of the occlusion, which IS given...) 146.199.60.87 (talk) 21:52, 11 August 2019 (UTC)


 * OKAY, RIGHT, FORGET THAT.
 * I spotted the "28 second" result from Camalau, and translated the document (Google Translate lets you upload PDFs now, joy).
 * And there's something VERY fishy going on.
 * * Exhibit A: a positive occultation result from Sao Luis, very nearly on the predicted centreline of the shadow path.
 * * Exhibit B: a positive occultation result from Camalau, which is actually slightly south of the predicted outer edge of the shadow and some 450km south compared to Sao Luis' position relative to the predicted shadow path (assuming a sizable polar axis, or at least equivalent diameter, of 966km, according to the MIT occultation proposal/organisation page linked to from the PDF - but currently appearing nowhere in the article?). Said result being more than 50% of the length of the Sao Luis one, suggesting that Varuna is actually quite large and circular - or alternatively, *extremely* lumpy.
 * * Exhibit C: a NEGATIVE occultation result from Quixada, which is IN-BETWEEN Sao Luis and Camalau, and closer to the former than the latter. No further details are given for this supposed (lack of) observation, unlike the other two.
 * Therefore, three possibilities present themselves:
 * 1) Varuna is actually a very closely-orbiting binary system, or at least has a very large moon, and somehow this was never noticed before.
 * 2) Varuna has an extremely irregular shape, possibly croissant-shaped, and it rotated such to occlude nicely north and south of Quixada, but not over the town itself.
 * 3) Varuna is actually larger and more spherical than otherwise expected - and more importantly, someone, most likely either the Quixada or Camalau crew, is telling porky pies. To be honest, I'm not sure which one to believe, but I would suspect given the extremely elongated shape that a 52.5-second reading on the centreline but nothing at all around 220km south would imply (or in other words, the c/a relationship is a little less than the most extreme estimate of 0.45 - when the best fit for previous data is more around 0.51 or 0.52 - and that's IF Varuna's rotation is perfectly aligned with its shadow's axis of travel across the Earth at that point, AND IF Quixada *barely* grazed the edge of the shadow instead of registering even a double eyeblink's worth of occlusion), along with a maybe roughly spherical, maybe also very elongated binary partner to that very wonky primary... it's probably the Quixada station that's lying. Then again, for the "668km" estimate to come good, without straying heavily into the upper half of the error range, the more extreme aspect ratios HAVE to be true, because that's the only way you get a volumetric mean which agrees with it with sufficient strength.
 * Comedy fourth option: Some other piece of Kuiper belt rubble randomly got in the way of the scopes either at Camalau (giving a false positive occlusion), and/or both there AND Sao Luis (falsely extending the length of the actual occlusion), and the Quixada station is telling the truth...?!
 * Either way up, this points to a sadly less than reliable result, and I don't know if its findings can really be believed without a confirmatory follow up. It just produces too many questions and potential, mutually conflicting possibilities (it being a binary would certainly explain previous strongly opposed measurements however?). It definitely bears some kind of annotation in the article, anyway, which I'll have to try and brew up. 146.199.60.87 (talk) 23:21, 11 August 2019 (UTC)
 * Thanks for your very insightful remarks. — JFG talk 01:46, 12 August 2019 (UTC)
 * At least someone cares :D ... and, man, I am SO done with this page. All I was originally after was sorting the dimensions vs diameter bit (as a sideline to trying to put together a personal list of 50 (originally 100 but I'm getting tired of it) Largest Solar System Things to draw a map), and it kinda snowballed.
 * Anyway, the annoying thing about this particular mystery is that the Camalau observation is mentioned in the abstract to the 2010 presentation, but only as another result that was "still being processed", and ... that's as far as it's inclusion, or the clash with Quixada, seems to have gone in terms of science or consideration of the implications. And of course we haven't got any real way of finding out the full detail of what was presented at the DPS meeting. Guess we'll just have to sit back and wait for a few years until some new follow-up study trains a much better quality scope and sensor towards the object and actually resolves it properly.
 * Unless the authors happen to troll across this wiki page, or are open to suggestions from randoms via email or something, anyway. 146.199.60.87 (talk) 02:03, 12 August 2019 (UTC)
 * Edit: Heck, just look at the Hubble picture. There's a definite lump growing out of the top-right of the otherwise relatively circular disc, which isn't even in line with a typical stretched-ellipsoid shape. It's far more reminiscent of the actual-telescopy pictures shown for other KBOs with as-yet poorly resolved satellites (or, say, a snowman seen from the vantage point of a treehouse). It's either irregular, or it's two bodies, I'd put money on that. 146.199.60.87 (talk) 02:21, 12 August 2019 (UTC)
 * We definitely need more observations. JWST maybe? — JFG talk 08:43, 12 August 2019 (UTC)
 * I've tagged some of your text with citation needed. Beware not to enter your own conclusions or hypotheses into the article text; that's against Wikipedia's original research policy. Best find a source that makes this analysis. — JFG talk 08:43, 12 August 2019 (UTC)

How the heck do we get all the notes to glomp together in a single block?
OK, so I put a note on the mass calculation in the infobox ... and added a Notes reflist at the bottom. All fine and dandy, that worked just as you would expect...

Then I put another note in the body text, expecting it would become #2 on the list... Nope! Somehow that's ALSO "note 1", and the only thing on the bottom-of-page Notes reflist, and the original note (still called "note 1") has suddenly retreated to the bottom of the infobox. Even though there isn't a reflist coded in there. What?!

I can't see any way to fix it. Never mind that the WP help pages are an incomprehensible jungle at the best of times, and didn't really give me much in the way of useful guidance when I looked before (mostly, I've just found pages with features on that I want to use, and copied-and-pasted them instead), but this seems to simply be at odds with the way even those say it should work.

Worse still, when I went back to another page where I've seen multiple notes used before (but with a different form of the code, using a strange "tag" based flavour of the wikimarkup, which I expected might offer a fix), including a mix of infobox and body text examples... it's now got the same problem, and I didn't even edit that one in-between! The disease is catching! HELP!

How do we fix this?! Because I'm totally at a loss... 146.199.60.87 (talk) 00:50, 12 August 2019 (UTC)
 * The best way to add footnotes is efn; see how I did it. — JFG talk 01:45, 12 August 2019 (UTC)
 * Beautiful, and elegant, thank you times a hundred. Afraid your edit of 01:44 and mine of 01:50 actually clashed, as I was in the middle of doing a major revision of the infobox, and I had to redo all the notes in order to merge it, but I ain't even mad, as that's a much neater and self-evidently much more effective way of achieving what I set out to do. I'll try to remember it for the future, but I have a terrible fear that I won't... :-/ (...and now I'm wondering if the notes should go below the references, as by this point they just look messy) 146.199.60.87 (talk) 01:58, 12 August 2019 (UTC)
 * By MOS:NOTES convention, footnotes are listed just above references. In some articles, footnotes can be added within the article, for example at the bottom of a table. See for example Apportionment in the European Parliament or List of the verified oldest people. Each invocation of notelist tallies up all efn notes up to that point. If you need something more sophisticated, you can place individual notes in groups, with the group parameter, and gain fine control of where each group is displayed. — JFG talk 08:34, 12 August 2019 (UTC)

Name 3
By late 2000 the minor planet numbering was up around 30500. Had they skipped 20000, or was the original 20000 given a new number? If so, what is its current number? 216.255.165.198 (talk) 18:34, 4 January 2020 (UTC)
 * No number was skipped. No probably hundred of thousands. Ruslik_ Zero 14:14, 5 January 2020 (UTC)
 * I think the 20,000 was an upcoming number, and they adjusted the timing so it would be available for Varuna. Number 19,000 (2000 RM60) was discovered on 2000 September 3, Varuna on 2000 November 28, so that's consistent. There was discussion of assigning Pluto number 100,000; too bad they didn't. — kwami (talk) 07:47, 24 November 2021 (UTC)
 * Kwami's correct. Numbers are assigned in batches; I suspect they noticed that the batch they were about to number (see the relevant MPC batch) contained 20000, and intervened to pull Varuna a little ahead so that it'd be (20000) instead of (20894), as it would've been if they did the usual thing and strictly followed the order of provisional designation. So I guess they could've done the same thing with Pluto and made it (135000); too bad they didn't. Double sharp (talk) 10:27, 24 November 2021 (UTC)