Wikipedia talk:WikiProject Astronomy

MainTalkAstronomical objects
(Talk)Eclipses
(Talk)Article ratingsImage reviewPopular pagesMembersWikidata

{{infobox astro object}} and {{infobox cluster}}

{{infobox astro object}} has been proposed to be merged with {{infobox cluster}} ; for the discussion see WP:Templates for discussion/Log/2014 December 21 -- 67.70.35.44 (talk) 04:58, 22 December 2014 (UTC)

I've gone through and fixed all the error where the astro object infobox was used when the cluster infobox was suitable. StringTheory11 (t • c) 05:36, 23 December 2014 (UTC)

Sardanaphalus‎ and I revamped the sh!t out of {{Infobox astro object}} today. I went through astro obj transclusions to make sure all old parameters were updated.   ~ Tom.Reding (talk ⋅contribs ⋅dgaf)  19:41, 23 December 2014 (UTC)

This issue is still open -- 65.94.40.137 (talk) 08:44, 22 January 2015 (UTC)

It turns out that "Pigsonthewing is indefinitely banned from adding, or discussing the addition or removal of, infoboxes." here as of 10 September 2013, but is now being reconsidered here (currently in the evidence gathering phase). The fact that he's been very active on this issue seems to violate that restriction. That should be enough, yes? Has anyone gone through that process?   ~ Tom.Reding (talk ⋅contribs ⋅dgaf)  23:26, 30 January 2015 (UTC)

Apparently the arbs clarified that the restriction does not apply to replacing one infobox with another better one. The case should really be discussed on its merits, rather than on the people involved. If every one opposes the proposal, it won't happen. Graeme Bartlett (talk) 00:18, 31 January 2015 (UTC)

• Tom Reding has also posted the same cmt here and here as well as on this page. POtheW's restrictions do not apparently include anything beyond articles. Tom your posts both poison the well and sidetrack the discussion, intended or not. Further the issue of how far these restrictions extend is under review. Might be a good idea to discuss content and not editors.(Littleolive oil (talk) 23:42, 31 January 2015 (UTC))

• I'm posting related information to areas where Infoboxes are being discussed, just as 65.94.40.137 posted to the top 3 sections of this talk page recently. This case is (or was, based on the original wording of the restriction on the administrators' noticeboard (which I made sure to include)) pertinent to those discussing the TfDs and should not be excluded from that discussion. However, I won't be posting, and haven't posted, anymore because I think that information is well-disseminated, and now because of the concerns you bring up (giving equal weight to both).   ~ Tom.Reding (talk ⋅contribs ⋅dgaf)  01:51, 1 February 2015 (UTC)

FYI, this was reopened, so is again under discussion -- 70.51.200.101 (talk) 21:21, 21 February 2015 (UTC)

At Wikipedia:Templates for discussion/Log/2015 February 21.   ~ Tom.Reding (talk ⋅contribs ⋅dgaf)  22:03, 21 February 2015 (UTC)

White space

In HIP 13044, it looks like the infobox produces the extra white space that shouldn't be there, but I can't find out where. Can anyone find it and fix it? Compare Lalande 21185, where the extra white space is not produced. --JorisvS (talk) 11:21, 10 February 2015 (UTC)

Unfortunately, this doesn't do it (otherwise I would have easily fixed it). I also couldn't find anything obvious (i.e. what I could see in there) in the infobox's templates. --JorisvS (talk) 11:37, 10 February 2015 (UTC)

Don't know, but I suspect the good article is messed up. The tag is there, but the rating doesn't appear. Instead an extra paragraph gets inserted. Lithopsian (talk) 12:00, 10 February 2015 (UTC)

Removing the tag altogether does not affect the white space. --JorisvS (talk) 12:22, 10 February 2015 (UTC)

Fixed now. Someone should probably look at the article rating. The talk page says class C, but it looks better than that. Not good article though, the review says ON HOLD. Lithopsian (talk) 13:58, 10 February 2015 (UTC)

I don't know, it looks pretty accurate. It does not quite look B-class to me. --JorisvS (talk) 09:11, 11 February 2015 (UTC)

Weird as hell : Category:Star

FYI, there's a category called Category:Star that is not about star -- 70.51.200.101 (talk) 06:11, 11 February 2015 (UTC)

That category appears to refer to Star (sailboat), and should be renamed. Modest Genius ^talk 11:19, 16 February 2015 (UTC)

Lyman Continuum Photons (LyC).

If anyone can help tidy up the article Lyc photon it would be helpful. There are no references at the moment on what could become a very useful article, given the research taking place on Reionization. Richard Nowell (talk) 12:00, 11 February 2015 (UTC)

Definitely an important article. I've moved it to Lyman continuum photons because I think it's a better title. Sam Walton (talk) 12:06, 11 February 2015 (UTC)

LyC and LyC photon redirects are missing Lyc photons/LyC photons/LyCs/Lycs -- 70.51.200.101 (talk) 05:32, 12 February 2015 (UTC)

Good move. Probably can't help with the re-directs. I'm interested in this because of an article I've put for submission which is at its draft stage and an article that already points to two more LyC leakers. I can't really help with the physics, but I'll endeavour to try and spruce up the LyC photon article. Richard Nowell (talk) 08:59, 12 February 2015 (UTC)

The above-mentioned draft is now a fully-fledged article: Tololo-1247-232. Richard Nowell (talk) 15:57, 12 February 2015 (UTC)

I've added another article which links with LyCs and is mentioned in several studies with Tol 1247. If anyone could glance over Haro 11 that would be appreciated. Richard Nowell (talk) 12:06, 12 March 2015 (UTC)

Tyep IIa supernova (redirect to Supernova )

What is a type IIa supernova?

By coincidence, I came across a reference to this in a journal. It is a Type Ia supernova (white dwarf explosion) within dense circumstellar material so that after at first looking like a type Ia, it develops hydrogen lines and starts to look like a type II. That's all I know. The Supernova article doesn't mention them, the IIA disambiguation page redirects them to Type II supernova which also doesn't mention them. After fixing a couple of mistaken references (typos?), there don't appear to be any other links to this page within Wikipedia. Lithopsian (talk) 21:55, 16 February 2015 (UTC)

Type IIa supernova is a hybryd IIn/Ia. For example, SN 2006gy or SN 2005gj. Ruslik_Zero 20:20, 19 February 2015 (UTC)

Diagram request

I have noticed that some articles have excellent astronomy diagrams and I thought if I could ask somebody for a diagram depicting pre- and post-encounter orbit of the Earth-grazing meteoroid of 13 October 1990, as was required at its talk page. I agree it would help the article, but I am not able to do it myself. Would this be possible? Thanks very much. --Jan Kameníček (talk) 13:17, 19 February 2015 (UTC)

Jan.Kamenicek, what sort of diagrams do you mean? Depending on what you're looking for, I could probably get one whipped up in a day or two. Primefac (talk) 15:23, 19 February 2015 (UTC)

(I was the one who suggested it on the article's talk page.) An image akin to the one showing Chelyabinsk meteor's pre-encounter orbit, one for before and for after its Earth encounter, though I think preferably without the fuzzy starry background. --JorisvS (talk) 15:32, 19 February 2015 (UTC)

Yeah, I'll see what I can do. Primefac (talk) 15:45, 19 February 2015 (UTC)

Done, comments welcome before I upload to Commons. Primefac (talk) 11:27, 24 February 2015 (UTC)

Quite nice that you have included two views. Could you include also the orbits of Venus and Mars? --JorisvS (talk) 11:30, 24 February 2015 (UTC)

Version 2, though it looks a bit more crowded with the extra text. Primefac (talk) 11:53, 24 February 2015 (UTC)

The extra planets definitely add clarity. I notice the side view has become slightly oblique, I take it because otherwise the orbits of the three planets are hard to clearly draw. What about an oblique view that is perpendicular to the orbit of the meteoroid, either before or after its encounter with Earth? And could you simplify the header by removing "of the EN131090", because that has no added value for our purpose. --JorisvS (talk) 12:01, 24 February 2015 (UTC)

As a reference, this is what it looks like perpendicular to the meteoroid (it's at a 70° incline), not sure if it skews the perspective too much. Primefac (talk) 12:13, 24 February 2015 (UTC)

I'd remove Venus and Mars from the side view, as including them forces you to misrepresent the vertical extent of the planets' orbits, which I think does more harm than the clarity added. But Venus and Mars help a lot with the top view. —Alex (ASHill | talk | contribs) 13:21, 24 February 2015 (UTC)

Adding planets is good. I personally like the side version with Venus and Mars as it is. I do not think that the slightly oblique view makes harm. The view perpendicular to the meteoroid makes sense too. Jan Kameníček (talk) 21:30, 3 March 2015 (UTC)

As for removing part of the header "of the EN131090", I think it should stay, because the header "Orbit before and after encounter with Earth" would not be understandable if the picture is seen outside the article. Another possibility is omitting the header completely with all the necessary explanation just in the caption (and in the summary section at Commons).
I think that there is agreement about the top view, but what about the side view? Maybe both versions (the slightly oblique one with Venus and Mars orbit and the one without the two added planets) could be uploaded no matter of the result of this discussion. The pictures need not be used only in the article, and some people might find it useful if they can find both alternatives at Commons. --Jan Kameníček (talk) 22:33, 5 March 2015 (UTC)

Do you think "EN131090" means something to our readers, then? Moreover, where could it appear outside that article? --JorisvS (talk) 09:03, 6 March 2015 (UTC)

If nothing else, with the "EN131090" it is quite clear that the picture depicts a certain meteoroid and is not a general example of a meteoroid orbit. I also think that many people might understand that the abbreviation contains the date and there is a certain (although very small) number of those who understand it completely. Some other way of determining can be used as well (like Earth-grazing meteoroid of 13 Oct. 1990, but it is quite long - maybe could be shortened to 1990 Earth-grazing meteoroid, but that is not very precise). I do not know if anybody will use the picture outside our article, but it is possible. Commons do not serve only for Wikipedia, they are a well-known source of free content for a growing number of people who use the Commons pictures for various purposes. --Jan Kameníček (talk) 11:04, 6 March 2015 (UTC)

How does "EN131090" communicate 'a specific meteoroid'?? Any specifier is unnecessary in the article itself and would only clutter the title. We could, however, upload another version that specifies the meteoroid in the title, but it'll have to be something that is actually informative, clearly specifying the object it is about. --JorisvS (talk) 11:53, 6 March 2015 (UTC)

Other meteoroids have different designations. However, I do not insist that it has to be there, I agree that it is not very informative for most readers. As I wrote, the meteoroid can be specified in a different way, or the header can be removed completely. I just think it would be misleading to upload the picture to Commons with the header saying simply "Orbit before and after encounter with Earth" without saying what it is the orbit of. This could be confusing to people who would find the picture directly at Commons and not in our article. If we decide to have it without the header, than the lines "Orbit before and after encounter with Earth" can be written to the caption under the picture in the article instead. --Jan Kameníček (talk) 22:23, 6 March 2015 (UTC)

Naturally, it would be mentioned in the image's description. I'm quite open to finding including an informative way of including a good specifier in the image. --JorisvS (talk) 22:50, 6 March 2015 (UTC)

Well, I must admit I failed to find a more informative specifier that would be brief enough, so if you do not like it the way it is, I suggest to upload the pictures without the header and include all the necessary information just into the description below the picture. Jan Kameníček (talk) 20:26, 7 March 2015 (UTC)

Unfortunately, the discussion has not attracted many contributors, and so I think we should come to some conclusion. I suggest two possible solutions: 1) Primefac as the author of the pictures can judge the arguments and decide which version would be best to choose, or 2) he can upload more versions to Commons, one of them will be used in the article temporarily (all of them are very good in some ways and any of them is better than the present situation without a diagram), and then the discussion can continue for as long time as needed. If the discussion finally results in a different version than the one temporarily placed in the article, it can be easily replaced, and the previous version will stay at Commons for anybody who finds it useful too. --Jan Kameníček (talk) 23:16, 9 March 2015 (UTC)

 Done You can fight over which version to include on the talk page (I've uploaded both). Primefac (talk) 21:22, 10 March 2015 (UTC)

Thanks a lot! --Jan Kameníček (talk) 21:28, 10 March 2015 (UTC)

Can published papers be considered primary sources?

So this question has likely been answered before but I can't find an answer to it right now. I'm considering writing an article on the EAGLE simulation, on which there are some published papers. These are written by the people making the simulations though, so are they considered primary sources, or does the refereeing and publishing process mean they can be used to establish notability? I ask this on a level applicable to all such situations rather than this one in particular. Thanks, Sam Walton (talk) 19:50, 19 February 2015 (UTC)

Published papers are surely primary sources. Some perhaps more reliable than others, but still primary sources. I imagine it would be odd for papers to be written by people not working on EAGLE? Be aware of other guidelines on promotion, single-use accounts, and all that sort of thing, but the worst that can happen for a good-faith article is it will get deleted, and most likely not even that for poor references. You could always run something up quickly in your sandbox and ask for opinions. Or post the sort of thing you're looking at for references here. Lithopsian (talk) 20:04, 19 February 2015 (UTC)

It is certainly true that a published paper by the authors of something does not establish notability of that thing as, despite the third party review process, it's ultimately not a third party source. Citations in published papers by third party authors might establish notability, but probably not. It is certainly not true that the topic of every cited published paper is notable. It's really secondary sources by third parties (news articles, books, and review papers by third parties, for example) on a topic that establish notability more clearly. Of course, published papers by the team are very much ok for verifiability.

I might consider a paper in a journal like Nature or Science to be sufficient to establish notability, since their review process explicitly requires notability (unlike most other journals), but still better to rely on third party news articles (which Nature and Science papers often generate). But there, for the paper to establish notability for a simulation, the simulation (not the science the simulation was used to produce) probably needs to be the focus of the paper -- it's unlikely that that criterion will be satisfied.

See WP:PRIMARY: "a scientific paper documenting a new experiment conducted by the author is a primary source on the outcome of that experiment".

However, you could make the argument that synthesis, often in the discussion section, of a published, refereed research paper is in some ways a secondary source for verifiability purposes, but it's still not third party. —Alex (ASHill | talk | contribs) 21:17, 19 February 2015 (UTC)

I have to admit I'd never read that policy. Seems that it was written for the humanities rather than the sciences ;) Denigrating primary sources might be appropriate when describing a historical or political figure, or a war, but for most scientific articles a primary source is the best place to go for basic data. So ... are we trying to determine notability or ascribe references to facts within an article already determined to be notable? I happen to know of this project, and I wouldn't like to say whether it is notable or not. If it *is* deemed notable then I'd have thought most references would be papers written by EAGLE team members or other associated Durham scholars, with very little second or third party material being available. Papers are just starting to come out, so maybe notability will be more obvious in another year or two. Perhaps another useful criteria is whether other articles in Wikipedia mention, or should mention, EAGLE? Lithopsian (talk) 21:31, 19 February 2015 (UTC)

But the primary source is just that, it'd need follow up to check the results, such as what happened to the BICEP2 results, or how candidate exoplanets have disappeared under the analyses of others into the noise background (other primary sources disputing the results of the original primary source). Though in these cases the secondary sources are just as bad as the primary ones. (unlike in the humanities, where secondary sources are better than primary ones) And in this field, tertiary sources are frequently out of date, so also bad, but for different reasons. -- 70.51.200.101 (talk) 05:05, 20 February 2015 (UTC)

Not all published papers are PRIMARY sources, some of them are SECONDARY sources, it would depend on what kind of paper it is. Indeed some would be TERTIARY sources (compendiums of research by others); For your purposes, papers written by the people behind the simulation are indeed PRIMARY sources -- 70.51.200.101 (talk) 05:01, 20 February 2015 (UTC)

Generally speaking, scientific papers and press releases are primary sources, which can be used to establish facts. Review articles, stories in the popular media etc. are secondary sources which can be used to establish notability and opinion about the topic. EAGLE has plenty of the former but few of the latter (I only found one in a quick search), so you might struggle to demonstrate notability. In contrast, the Millennium Simulation has lots of coverage in the popular media. Modest Genius ^talk 13:17, 20 February 2015 (UTC)

If it makes sense to include results from the EAGLE simulation in a relevant article, like galaxy formation and evolution, there's no need to establish notability (since it's not a separate article), and published papers are certainly fine (and best) for that. —Alex (ASHill | talk | contribs) 15:15, 20 February 2015 (UTC)

Agreed, although I would be careful about adding results to that article from simulations which have yet to be confirmed via observations. Modest Genius ^talk 21:48, 23 February 2015 (UTC)

Amendment to Celestial bodies section - paragraph 2 at MOS:CAPS

Discussion at Amendment to Celestial bodies section - paragraph 2 Cinderella157 (talk) 01:42, 20 February 2015 (UTC)

Yet another discussion about capitalising Universe etc.? WT:MOSCAPS is looking decidedly dysfunctional at this point - the topic has been discussed to death. I've made my opinion clear in the earlier discussions, and see no reason to keep repeating it. Modest Genius ^talk 13:22, 20 February 2015 (UTC)

This current proposal is about the uncontroversial second paragraph of MOS:CELESTIALBODIES. Still haven't gotten close to a resolution on "Universe", and parallel discussion of "Solar System" is just beginning, likely to be followed by "Sun", "Earth", "Moon", and possibly every single word in the English language. The main new substance of the discussion of this paragraph (in my distillation) is the suggestion that we no longer explicitly base the Wikipedia MOS on the IAU MOS. —Alex (ASHill | talk | contribs) 15:04, 20 February 2015 (UTC)

Prefixes for light-year

This topic really confuses me. It first came from M104 when it is stated distanced 28 "megalight-years" away. Personally I oppose adding prefixes on the light year because it sounds crazy. There is no even "megalight" thing. Given that parsec is the standard, it's OK for me. However, is it acceptable to add prefixes on light year (i.e. Kilolight-years, Gigalight-years)? SkyFlubbler ^(talk) 02:03, 21 February 2015 (UTC)

I agree that writing out mega-light year (whatever the exact form is) is weird and non-standard. I've seen Mly in non-major textbooks, so that at least exists outside of Wikipedia, though it's still a little strange. For distances large enough so that SI prefixes are helpful, I'd just use kpc or Mpc. —Alex (ASHill | talk | contribs) 02:10, 21 February 2015 (UTC)

Sorry, I realize that was unclear: by "non-major textbooks" I mean astronomy textbooks intended for introductory undergraduate survey courses for non-astronomy majors; an otherwise-good textbook I taught from actually specified the Hubble constant in km/s/Mly, written that way. So kly and Mly may not be standard in research literature, but it's not a usage that we're making up from whole cloth. As far as I'm concerned, if "ly" is clear, "kly" and "Mly" are perfectly clear, just stylistically odd. —Alex (ASHill | talk | contribs) 15:31, 21 February 2015 (UTC)

I don't think the usage of prefixes of light year is a standard. No arXiv paper has ever given a prefix for light year. Also, it is not an accepted standard to put it in a prefix, just a unit uulsed so people can understand it. SkyFlubbler ^(talk) 02:50, 21 February 2015 (UTC)

When not written out, it is simply like kpc and Mpc. It is a simple matter of using the standard SI prefixes with the light-year unit. For such large distances I would like light-year values, at least alongside the corresponding parsec values, because I have an easier time interpreting those. --JorisvS (talk) 09:05, 21 February 2015 (UTC)

Use of SI prefixes with the light year seems unwise to me. If you can't get the message across with parsecs, say it in millions of light years instead. Dondervogel 2 (talk) 12:20, 21 February 2015 (UTC)

It'll depend on the reader whether parsecs or lightyears is clearer. For me, it's lightyears, because its association with light's travel time (though not necessarily the time light has actually travelled due to the expansion of the Universe), whereas the corresponding association for parsecs is not meaningful. Things like "millions of light-years" are rather wordy and cannot always be used (e.g. in infoboxes). What would be the problem with "Mly" anyway (I concur that "megalight-years" looks weird)? --JorisvS (talk) 14:42, 21 February 2015 (UTC)

There is no international standard symbol for the light year (ISO 80000-3 suggests the abbreviation "l.y.", but no symbol), whereas for the parsec the symbol pc is recognised. I think Mpc is OK but not Ml.y. Dondervogel 2 (talk) 16:28, 21 February 2015 (UTC)

For what it's worth, I think kly, Mly, Gly are both intuitive (especially if wikilinked) and visually appealing. I prefer pc, Mpc, Gpc myself, but *ly are an adequate alternative. I would cringe if I saw *l.y., *LY, etc.   ~ Tom.Reding (talk ⋅contribs ⋅dgaf)  16:58, 21 February 2015 (UTC)

Dondervogel, why would "Mly" no be okay ("Ml.y." and "MLY" are wholly different with the weird full stops and caps)? It's a simple combination of the unit "ly", commonly used at Wikipedia and elsewhere, and a standard SI prefix. --JorisvS (talk) 19:48, 21 February 2015 (UTC)

My point is that the International System of Quantities does not recognize ly as a symbol for light year, but I accept ISO is not the only relevant authority. What symbol does the IAU advise for light year? Dondervogel 2 (talk) 21:20, 21 February 2015 (UTC)

I found the statement "An appropriate unit of length for studies of structure of the Galaxy is the parsec (pc), which is defined in terms of the astronomical unit of length (au). The unit known as the light-year is appropriate to popular expositions on astronomy and is sometimes used in scientific papers as an indicator of distance." at [1], which strengthens my feeling that there is no internationally accepted symbol for light year. Dondervogel 2 (talk) 21:26, 21 February 2015 (UTC)

What's the added value of it being defined in terms of the AU? The AU is an arbitrary value close to the average distance from the Sun that Earth just happened to have, which only corresponds to SI units because it is set to exactly 149597870700 m. Of course the light-year also has this, with the Julian year (exactly 365.25 days, or 31557600 s) being set close to the actual orbital period of Earth. The speed of light is, by definition, exactly 299,792,458 m/s, with the length of the meter derived from it. The only natural symbol in line with those of the SI, and that of the parsec, is "ly". The use of SI prefixes is also immediately clear to anyone familiar with them. What is the actual problem with it exactly? --JorisvS (talk) 22:08, 21 February 2015 (UTC)

I see nothing wrong with use of the light year in principle, but I do not agree that the only natural symbol for this quantity is "ly". That symbol is recognised neither by the ISQ nor by the IAU, and that is the problem. Dondervogel 2 (talk) 22:22, 21 February 2015 (UTC)

Had written a reply to your earlier comment with that link before I saw you'd already posted it. I guess the reason this doesn't come up is that in popular writing about astronomy, you wouldn't normally expect your reader to understand SI prefixes but also wouldn't be using numbers often enough for "23 million light-years" to get awkward. A lot of the scientific material on Wikipedia gets technical enough that it would be ugly and insulting to the readers who are interested in our more technical articles to say "millions" or "billions" to avoid using prefixes. So I guess, to me, that may be an indicator of time to switch to the IAU-recommended units (pc, kpc, Mpc, Gpc). But I'm also fine using ly; since it's not a standard unit symbol, it should be defined at first use in each article in which it's used, which is easy enough. —Alex (ASHill | talk | contribs) 00:54, 22 February 2015 (UTC)

FWIW, I don't see a problem with the current status quo either. StringTheory11 (t • c) 01:03, 22 February 2015 (UTC)

Why can't we change the {{convert}} to display "lightyear" instead of "light-year"? Then "megalightyear" wouldn't have that weird dash problem. -- 70.51.200.101 (talk) 08:30, 22 February 2015 (UTC)

A quick google search reveals that the cgs unit of energy flux density langley (symbol Ly) is often written as ly (try eg mly/min). Pure speculation on my part, but that might be the reason that neither ISQ nor IAU accept the symbol ly for light year. What is not speculation is the empirical fact they do not, which seems a good reason to avoid this symbol where possible. Dondervogel 2 (talk) 12:51, 22 February 2015 (UTC)

The Langley and the light year are such different units that I think the potential for confusion is minimal: it will nearly always be clear in context. And when it's not, spell out the unit. The fact that there's no standard symbol doesn't mean we can't define a symbol on an article-by-article basis. And Zeilik (2002). Astronomy: The Evolving Universe. ISBN 0521800900. is a book that uses this exact convention, for example. —Alex (ASHill | talk | contribs) 21:31, 22 February 2015 (UTC)

So what do you suggest as a better symbol? The unit itself is too common to not be used. --JorisvS (talk) 16:39, 22 February 2015 (UTC)

I think if the major international astronomy and standardization bodies do not define a symbol, Wikipedia should not either. Instead, why not use the abbreviation l.y., endorsed by the ISQ and IEEE? (I'm not sure about the IAU) Dondervogel 2 (talk) 16:51, 22 February 2015 (UTC)

What's with the strange and unusual periods? In normal unit symbols there are none of those. --JorisvS (talk) 16:56, 22 February 2015 (UTC)

It's an abbreviation, not a symbol. It is quite common to punctuate abbreviations, for example "sec." for second or "lb." for pound. The difference is that abbreviations are intended to replace words in sentences whereas a symbol is used to represent a unit in an equation. Dondervogel 2 (talk) 18:00, 22 February 2015 (UTC)

Almost exactly: Units represent the dimension associated with a number, whether or not this is in an equation. When used in combination with a number it is a unit, not an abbreviation, just like the AU or m are, regardless of whether there is any official recognition. And when used in a sentence without a number, it is better to write it out. --JorisvS (talk) 18:28, 22 February 2015 (UTC)

I think the main source of the problem is a paragraph on the Light year article. It's stated as this:

:"Metric prefixes are occasionally applied to the light-year. Thus one thousand, one million and one billion light-years are sometimes called a "kilolight-year", a "megalight-year" and a "gigalight-year" (abbreviated "kly", "Mly" and "Gly") respectively."

Unfortunately, this paragraph doesn't have any sources or references. Is the statement reliable enough? SkyFlubbler ^(talk) 10:43, 24 February 2015 (UTC)

@SkyFlubbler: I think the statement should be removed. Reliable sources either use parsecs or turn to constructs like "billion light years". I have seen light-gigayear (which makes more sense than gigalight-year) but that too is rare. Dondervogel 2 (talk) 18:49, 9 March 2015 (UTC)

Use of megalight-year by convert template

I've just noticed a problem with NGC 3267. That article uses "megalight-years", but when I tried to rewrite as "million light-years" I was unable to, as the problem seems to be embedded in the convert template. Does anyone know how to fix that? Dondervogel 2 (talk) 18:53, 22 February 2015 (UTC)

{{convert | 1 | e6ly | e6pc}}: 1 million light-years (0.31×10^⁶ pc) —Alex (ASHill | talk | contribs) 20:31, 22 February 2015 (UTC)

It would be better if {{convert}} used "lightyear" instead of "light-year", then the prefix could attach normally without the dash issue -- 70.51.200.101 (talk) 06:53, 23 February 2015 (UTC)

That would solve one problem and introduce a new one, which is that the unit is light year (ISQ) or light-year (IAU). Calling it a lightyear would be contrary to both. Dondervogel 2 (talk) 07:08, 23 February 2015 (UTC)

Then can {{convert}} be forced to add a dash after the prefix? mega-light-year ? That would also fix the dash issue in a more awkward manner. If not, then I think it would be better to use "lightyear" as {{convert}} makes the formulation "megalight-year" an incorrect statement. (it should be "mega light-year" or "mega-light-year" instead) -- 70.51.200.101 (talk) 08:12, 23 February 2015 (UTC)

"mega light-year" is just plainly incorrect. --JorisvS (talk) 12:57, 23 February 2015 (UTC)

I found this book that uses the term light-gigayear, with symbol Gly to define the hubble (apparently 1 hubble = 1 Gly). This might be a way out but it is not standard, seems rarely used and I have so far found neither light-megayear nor light-kiloyear. Apart from this example, where are the units kly, Mly and Gly used outside Wikipedia? Dondervogel 2 (talk) 07:23, 24 February 2015 (UTC)

Board of Longitude

Wikimedia UK and the National Maritime Museum are holding an editathon one the 15th April to improve articles related to the Board of Longitude. Members of this project are very welcome to attend, or to make suggestions as to articles that could be improved by this or outstanding queries that the NMM experts might be able to answer. I have already found ten talkpages with outstanding queries that I hope are related to the measurement of longitude. Any suggestions/ queries gratefully received on Wikipedia:Meetups/UK/National_Maritime_Museum_April_2015 or Wikipedia talk:Meetups/UK/National Maritime Museum April 2015. Jonathan Cardy (WMUK) (talk) 17:37, 23 February 2015 (UTC)

Accelerating universe discussion at WP:PHYS

There was a discussion started at WP Physics regarding some 116 IP edits of unknown accuracy, that could probably use some WP:AST attention. Primefac (talk) 20:40, 23 February 2015 (UTC)

The two editors contributing the changes, mostly 188.242.42.246 (talk · contribs) with some from 89.110.4.185 (talk · contribs) both appear to be editors in Russia (PPPOE ISP addresses) from two different ISPs; but both are in Saint-Petersburg -- 70.51.200.101 (talk) 04:50, 24 February 2015 (UTC)

Distance categories

I came across the bizarre Category:Objects within 100 Gly of Earth, which would logically include every object in the observable universe. It's an extension of other categories at other distances. There's a discussion going on at CfD on all of them, which would benefit from involvement from those familiar with astronomy. Modest Genius ^talk 23:31, 24 February 2015 (UTC)

Now that the 100Gly category has been deleted, we need to fix the rest of that category tree -- 10 ly, 100 ly, 1kly, 10kly, 100kly, 1Mly, 10Mly, 100Mly, 1Gly, 10Gly -- 70.51.200.101 (talk) 08:03, 5 March 2015 (UTC)

We could reorganize it to make the 10 ly cat Category:Nearest stars and brown dwarfs, alongside List of nearest stars and brown dwarfs. I'm not sure if the same distance limit should be applied. And maybe we could also make a Category:Near stars and brown dwarfs for stars and brown dwarfs that are close, but not quite as close as the nearest ones. --JorisvS (talk) 12:30, 5 March 2015 (UTC)

The category tree has been nominated for deletion, see Wikipedia:Categories_for_discussion/Log/2015_March_8#Objects_by_distance_from_earth -- 70.51.200.101 (talk) 04:12, 10 March 2015 (UTC)

More categories nominated for deletion

See Wikipedia:Categories for discussion/Log/2015 February 25. Nominated so far are Category:Objects named with variable star designations, Category:Flamsteed objects, and Category:Bayer objects, if anyone has opinions on this. I hope they survive, though I cannot really express a reason to keep other than ILIKEIT. — Huntster (t @ c) 21:15, 25 February 2015 (UTC)

I've !voted there, with what I think are valid reasons to keep. Modest Genius ^talk 22:42, 25 February 2015 (UTC)

see Wikipedia:Categories for discussion/Log/2015 February 26 for more categories, including Category:Stars with proper names -- 70.51.200.101 (talk) 07:17, 27 February 2015 (UTC)

Zero-energy universe

I have just reverted massive changes to Zero-energy universe. I would welcome an alternate point of view at the article talk page. --Hroðulf (or Hrothulf) (Talk) 15:28, 1 March 2015 (UTC)

Who the hell are you? 91.122.2.96 (talk) 16:18, 1 March 2015 (UTC)

91.122.2.96 (talk · contribs) has been blocked -- 70.51.200.101 (talk) 05:09, 2 March 2015 (UTC)

Reference Formula Policy for Exoplanets

Note:discussion originally placed at Wikipedia:Village pump (policy)/Archive 118#Reference Formula Policy for Exoplanets Oiyarbepsy (talk) 15:34, 2 March 2015 (UTC) Proxima Centauri#References

This reference section has a formula in it, which in most cases would be considered Original Research and purged from the article ASAP. But apparently there are exceptions to the rule/policy. What I don't understand is why Wikipedians continue to allow Wikipedia to look foolish with articles that claim many newly discovered planets are a "twin of earth" when there are simple formulas, just like the one used in the Proxima article, that show the solar constant or Flux (Irradiance/Isolation) of the planet. Article after article with new planets in the "habitable zone" that are actually receiving much more heat than Venus or much less heat than Mars, but since they are very technically in the "habitiable zone," editors over look that and reference article that call it a twin of Earth, or reference articles that call them a twin of Earth.

Planetary equilibrium temperature#Calculation for extrasolar planets

I know some articles are showing the flux received in the planet's stats box but it should be a policy.
It should be standard if the Semi-major axis and the Luminosity (or Radius & Temperature) of the star are known.

f = L/d²
...or...
f = [(R²)(sbc)(T⁴)]/d²

${L}_{\bigodot }=\left(4\pi {{R}_{\bigodot }}^{2}\sigma {{T}_{\bigodot }}^{4}\right)$
σ = 5.670374419...×10⁻⁸ W⋅m⁻²⋅K⁻⁴ , ...Stefan-Boltzmann constant

because ${L}_{\bigodot }=\left(4\pi {f}{d}^{2}\right)$
then...

${SolarConstant}=\left({R}_{\bigodot }^{2}\sigma {{T}_{\bigodot }}^{4}\right)/D^{2}$
${SolarConstant}=\left(\left({0.0850}^{2}\right)\left({5.670373}E^{-8}\right)\left({4715}^{4}\right)\right)/0.26^{2}=1683.678$ $W/m^{2}$
An example in HD 85512 b which shows it receives more heat than Earth, 1366.078/1683.678 = 123%.

Another well established formula
$T={\sqrt[{4}]{\frac {(1-a)S}{4\epsilon \sigma }}}$
where Wikipedians can just plug in the numbers is at the article subsection Zero Dimensional Climate Models

Can someone explain how I can start a committee or a policy review or whatever it takes to solve this problem?
So that we don't continue to see these articles that get away with false claims of discovered Earth twins.

Calculating the Flux received by a planet is not problematic. As I've illustrated it can be done with two or three known values.
You want an example of planets that aren't what the are supposed to be, Gliese 581 c used to have references saying it is a Earth-like,
where as now it's more truthfully saying it's more likely a Super-Venus. An extra solar planet article should certainly never start like this
There is no reason why the "Planetbox" shouldn't contain the Flux by now,
as other stats boxes (eg. Kepler-186f) are starting to include them for other exoplanets.
This list of "Confirmed small exoplanets in habitable zones" is one that can be checked for misleading suggestions.
Kepler-186 f could receive as little as 10% of the heat the Earth receives and the Planet Characteristics portion of the stat box don't add up.
It says 41% while the Equilibrium Temperature is -30°C. Kepler-438b is another one with contradictory stats,
"announced as being located within the habitable zone of Kepler-438." Where as at every point in its orbit it receives much less heat than Mars.
To me it simply a matter of stating the mathematical facts, rather than only speculations of Astronomers.
A policy that insisted the Flux can be calculated before habitability can be discussed in a article would go a long way to establish truthful rather than overly speculative articles. This is a simple solution to a problem I find distressing.

24.79.36.94 (talk) 10:05, 28 February 2015 (UTC)

Responding to the question "Can someone explain how I can start a committee or a policy review or whatever it takes to solve this problem?": Why is a committee necessary? Calculating a density qualifies as a routine calculation (WP:CALC), as far as I'm concerned, but it doesn't hurt to show the calculation explicitly in a nb footnote (not a reference) as is done in Proxima Centauri. Determining "habitability" is much more subjective and should almost certainly be left to be explicitly stated in references; establishing any Wikipedia policy to say that the flux must be calculated before determining habitability seems to be requiring original research. —Alex (ASHill | talk | contribs) 16:01, 2 March 2015 (UTC)

"Stargazer"

The naming, usage and primary topic of Stargazer is under discussion, see talk:Stargazer (disambiguation) -- 70.51.200.101 (talk) 06:02, 3 March 2015 (UTC)

Crosspost from WP:SOLAR

I have a post on the WP Solar System talk page regarding Martian craters. I know that project is not as active as this one so I thought I'd garner more opinions. Primefac (talk) 12:59, 5 March 2015 (UTC)

Planetary habitability

I have nominated Planetary habitability for a featured article review here. Please join the discussion on whether this article meets featured article criteria. Articles are typically reviewed for two weeks. If substantial concerns are not addressed during the review period, the article will be moved to the Featured Article Removal Candidates list for a further period, where editors may declare "Keep" or "Delist" the article's featured status. The instructions for the review process are here. DrKiernan (talk) 10:01, 7 March 2015 (UTC)

LQG: Large quasar group vs. Loop quantum gravity

I find this one practically confusing, as to what simplification is correct. What is the standard for LQG? SkyFlubbler ^(talk) 00:30, 12 March 2015 (UTC)

Both One is an astronomy topic, the other is a physics topic. It is no more confusing than any other abbreviation with multiple uses. They are used in different regimes, so where one appears the other will not. -- 65.94.43.89 (talk) 04:00, 12 March 2015 (UTC)

Mike Brown, the eccentric

Thought I'd share a laugh. We say the following in our article on Mikebrown:

"Mikebrown is unusually eccentric and not very bright. ... Astronomers have not noticed any outbursts by Mikebrown."

I'm waiting for the audio version. Poor Mike! — kwami (talk) 18:40, 16 March 2015 (UTC)

Delightful. It ought to go in the astronomer's biography. He doesn't seem the kind of guy who would get in a tizzy about it. Jim.henderson (talk) 13:51, 18 March 2015 (UTC)

Nomination for deletion of Template:Star systems within 20–25 light-years, etc.

Template:Star systems within 20–25 light-years, and several related templates, have been nominated for deletion. As these templates are within the scope of WikiProject Astronomy, you are invited to comment on the discussion at these templates' entry on the Templates for discussion page. Dirtlawyer1 (talk) 23:31, 18 March 2015 (UTC)