Wikipedia talk:WikiProject Astronomy

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WikiProject Astronomy (Rated Project-class)
WikiProject icon Wikipedia:WikiProject Astronomy is within the scope of WikiProject Astronomy, which collaborates on articles related to Astronomy on Wikipedia.
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Lua and Stellar Luminosity

It looks like the Lua language supports the math.exp() function, so in theory it should be possible to request a Lua module that can convert the log of stellar luminosity ± error margin into L* ± σL* using the appropriate propagation of uncertainty function. How do we feel about that? Sources such as Joffre et al. (2015) present the stellar luminosity in the former format (logL ± e_logL) whereas Wikipedia articles use the latter, so a template conversion of the error margin could be useful for that purpose. (Note that we're already doing something comparable with the parallax -> distance conversion in the starbox.) Praemonitus (talk) 21:36, 16 December 2017 (UTC)

I regularly convert published log(L) values into a linear L value, but I rarely propagate the error margins. Partly from laziness, but also because of lingering doubts about what the appropriate propagation function should be. I know it is well-defined statistically, but astronomical margins of error tend not even to be statistically sound. This is nicely shown by the parallax example, where we do usually have a statistically sound margin of error in the parallax but even the most likely distance is not a simple inverse of the parallax. Read for more statistics than you ever wanted to know. Lithopsian (talk) 21:50, 16 December 2017 (UTC)
I understand the conversion is at best an approximation, but as a reader I find it useful to get some idea of the accuracy of the data. Praemonitus (talk) 22:26, 17 December 2017 (UTC)
Could also look at bolometric magnitudes which are still sometimes given instead of luminosities. Lithopsian (talk) 19:21, 18 December 2017 (UTC)
An alternative could be to use the upper-lower bound method for the propagation of uncertainty. That involves computing the value with the error margin added/subtracted, then perform the exponentiation of the results. Praemonitus (talk) 21:47, 26 January 2018 (UTC)
It looks like the technical term for this type of approach is "probability bounds analysis", with the result providing a p-box. Praemonitus (talk) 17:23, 6 February 2018 (UTC)

NGC navboxes

The NGC navboxes have a problem where some templates like {{Ngc5}} and {{Ngc80}} look different from other ones like {{Ngc15}} and {{Ngc20}}. In particular, the former has NGC designations shortened to include just their number whereas the latter has NGC designations unshortened (sort of like 499 vs. NGC 5585). What should be done about this? Loooke (talk) 16:01, 7 January 2018 (UTC)

The links should be piped. If you're in an NGC navbox it should be fairly obvious that the links are to NGC objects; additionally, for size/length purposes. Assuming there's no major objections I'll pipe everything tomorrow. Primefac (talk) 14:47, 8 January 2018 (UTC)
Pipe them. Nice catch Loooke.   ~ Tom.Reding (talkdgaf)  15:36, 8 January 2018 (UTC)
 Done. I also default-uncollapsed {{Ngc40}} & {{Ngc55}}, which were the only 2/16 that were default-collapsed.   ~ Tom.Reding (talkdgaf)  15:11, 11 January 2018 (UTC)
Thanks! Loooke (talk) 21:26, 18 January 2018 (UTC)

I love Astronomy!

How can I help with WikiProject Astronomy?

(Date: 1-8-2018)

 - Out of this World Adventure 🌎 (Talk)
You could look at Category:Astronomy articles needing attention and see what you can assist with. Graeme Bartlett (talk) 12:00, 9 January 2018 (UTC)
Also, Category:Astronomy articles needing infoboxes has exactly that: astronomy-related articles that need infoboxes. Loooke (talk) 23:08, 9 January 2018 (UTC)
A number of which don't satisfy WP:GNG. Praemonitus (talk) 15:50, 11 January 2018 (UTC)
There's also CATEGORY: Draft-Class Astronomy articles and CATEGORY: Astronomy stubs -- (talk) 05:15, 3 February 2018 (UTC)

Updated: Pages in Category:Astronomy (1 & 2)

A while ago some people found this useful. I updated it at the end of 2017, and just wanted to let those who've used/been using it know.   ~ Tom.Reding (talkdgaf)  14:11, 13 January 2018 (UTC)

@Tom.Reding: Could you compile a version without redirects? This would be useful for User:Bibcode Bot. Headbomb {t · c · p · b} 14:31, 30 January 2018 (UTC)
 Working.   ~ Tom.Reding (talkdgaf)  14:59, 30 January 2018 (UTC)
@Headbomb:  Done! I created the following suite of pages:
all listed at the top of each page, for easy navigation.   ~ Tom.Reding (talkdgaf)  12:48, 31 January 2018 (UTC)

Proxima Centauri Image Caption

A now somewhat lengthy debate regarding a caption to an ESO orbital plot of Proxima Centauri could use some additional perspectives as its getting rather redundant. Please take a look if you are interested. Thank you. Praemonitus (talk) 04:09, 21 January 2018 (UTC)

When was the last super blue blood moon?

Hi. My friends over at Wikipedia:Reference desk/Science#Super blue blood moons are having difficulty in focusing on what I want to know. Can any of you good people help out?

Thanks. -- Jack of Oz [pleasantries] 18:16, 26 January 2018 (UTC)

Good luck with that. Very different answers depending on your definition for blue moon and super moon, and your location, plus how picky you are about the depth of the eclipse. FWIW, 1868 doesn't look like a good year: it has a blue moon (two full moons in October for most of the world), but no total (or even partial umbral) lunar eclipses and no eclipses at all in October, so that's a dud. Lithopsian (talk) 18:47, 26 January 2018 (UTC)
It's a pretty meaningless question. Those terms are not well-defined, and seem to be picked arbitrarily by the authors of press releases to make their event sound rarer or more exciting. Supermoon#Definitions discusses some of the variations defining a supermoon, there are two different definitions of a blue moon etc. Why does anyone care anyway? These are entirely arbitrary categories. Modest Genius talk 20:31, 26 January 2018 (UTC)
Ok, let me put it this way. There are different definitions for "super moon" and different definitions for "blue moon". If we take one of each of those definitions, and ask the question "When did they last coincide?", we can come to a meaningful answer. Then, if we add total lunar eclipses into the equation and ask "When did a lunar eclipse, super moon and blue moon last coincide?", we can come to a different meaningful answer. I want that answer. -- Jack of Oz [pleasantries] 05:35, 27 January 2018 (UTC)
Why? What possible use would it be to anyone? This might help. Besides, you're the one asking the question, so you need to specify exactly which criteria you're using. Modest Genius talk 13:36, 29 January 2018 (UTC)
I've seen reports also about 1866. In 1866, there was a full moon on Mar 1st and Mar 31st, over most of the Earth's surface. There was a total lunar eclipse on Mar 31st, again widely visible. However, apogee occurred on April 3rd, so it would be hard to call it a supermoon. The perigees in mid-March and mid-April were also not particularly close ones. November 22nd 1866 is a decent supermoon candidate, closest perigee of the year and only 5 hours after the full moon. Lithopsian (talk) 16:04, 1 February 2018 (UTC)

Charts comparing solar analogs to the Sun

Every so often I see charts comparing solar analogs to the Sun. Examples are at Iota Horologii, Kepler-29, and 18 Scorpii. Do we really need these comparison charts? Personally I'd just mention somewhere in the article that the star is similar to the Sun, without needing to compare all the properties.

Sometimes these charts are accompanied by very weasel-wordy text, which goes like this: "To date no solar twin with an exact match as that of the Sun has been found, however, there are some stars that come very close to being identical to that of the Sun, and are such considered solar twins by the majority of the public." What to do with this? Loooke (talk) 23:41, 29 January 2018 (UTC)

I don't see the need for distance and coordinates in those charts. Praemonitus (talk) 00:21, 30 January 2018 (UTC)
Same here, they are fully redundant to the infobox (or, for Kepler-29, inconsistent). --mfb (talk) 03:57, 30 January 2018 (UTC)
Remove 'em. If there's a comparison to be made, it can be done in prose (without the weasel words of course). Primefac (talk) 13:41, 30 January 2018 (UTC)
Nuke'em. Headbomb {t · c · p · b} 13:44, 30 January 2018 (UTC)
Ok, I've removed all of the charts and the accompanying text. Loooke (talk) 20:56, 30 January 2018 (UTC)

Peer review for David Meade (author)

If anyone wants to give feedback about my article, go to the peer review page and feel free to do so. --LovelyGirl7 talk 22:45, 1 February 2018 (UTC)

Please review Herbig-Haro object for GA criteria


Herbig-Haro object is a former feature article within the scope of WikiProject Astronomy, and was delisted mainly due to insufficient citations. I have been improving the article for some time and citation concerns have been addressed, along with some other improvements. As such, I have nominated it for GA and would like to request willing editors to review it.

Best regards--ubedjunejo (talk) 22:56, 18 February 2018 (UTC)

A link to a DAB page

Baryon asymmetry links to the DAB page metagalaxy (as a pipe from metagalaxies). Can any expert here help solve the problem? Narky Blert (talk) 12:30, 20 February 2018 (UTC)

I think the inclusion of that DAB link is a misunderstanding. Metagalaxy is not a synonym for anti-matter galaxy. Rather it refers to an amalgamation of galaxies, anything from a galaxy group up to the entire observable universe. For a while, it was theorised that some of these metagalaxies (ie. groupings of galaxies) might be composed of anti-matter and a description of that could have been mis-read. Lithopsian (talk) 14:38, 20 February 2018 (UTC)

Main image of Pleiades under copyright?

Was just browsing the article on the Pleiades, and I noticed that the main image is from the Digitized Sky Survey, supposedly under public domain because it's sourced from a NASA release. I was surprised, because I thought DSS images were under copyright, and confirmed that they indeed are. I'm not an expert in copyright info, but something seems inconsistent here. Does NASA using the file mean it's no longer under copyright? Did they make a mistake in using a copyrighted file without permission, or did wikipedia make a mistake in assuming that their use permits free usage. Something overall seems somewhat fishy here. BTW while we're at it, there's a few other images coming directly from DSS and such without any such NASA backup in [1], such as this and this. exoplanetaryscience (talk) 01:39, 25 February 2018 (UTC)

From what I can find, File:Pleiades large.jpg was created by the STScI at Palomar, and is thus released from copyright. We use {{PD-USGov-NASA}} because STScI operates under NASA contract NAS5-26555. I cannot speak for other images in Commons:Category:Digitized Sky Survey, however, and it's likely their individual releases would have to be determined. It appears most of the DSS is based off scans by STScI of photographic plates produced by the UK Schmidt Telescope. I don't see how these could be justified for our use, but I could be missing some other detail. Huntster (t @ c) 02:41, 25 February 2018 (UTC)
From what I can find, File:Pleiades large.jpg was created by the STScI at Palomar, and is thus released from copyright.
Is that true though? Indeed the DSS Copyright Information expressly states the Palomar data is "copyright © 1993-1995 by the California Institute of Technology" and at the same time as referencing the NASA contract. IANAL, but our very own article on copyright status of work by the U.S. government states in the opening paragraph;
Publication of an otherwise protected work by the U.S. government does not put that work in the public domain. For example, government publications may include works copyrighted by a contractor or grantee; copyrighted material assigned to the U.S. Government; or copyrighted information from other sources.
This would imply contracted work is not necessarily free of copyright. ChiZeroOne (talk) 12:13, 25 February 2018 (UTC)
A very dubious area. There are lots of images hosted at places like STScI, which have been constructed from copyright images (eg. DSS) with the addition of other wavelengths or annotations. Without being an intellectual property lawyer and examining the small print in minute detail it can be difficult to tell what the status of these images is. Wikipedia editors have a terrible habit of assuming everything is free unless there is a massive copyright symbol stamped on it in red, but then I guess it isn't their necks on the line. In this case, there is an image use link right next to the image. The linked page contains the usual mystifying text about images being credited to STScI being free-to-use and other images *possibly* being copyright. In this case the image is unhelpfully credited to "NASA, ESA, and AUAR/Caltech". The credit isn't explicitly STScI, but those institutions are collectively and effectively STScI; they certainly aren't the DSS copyright holders for that image. I'd say we're good with this one, but then it isn't my neck on the line and I'm not an intellectual property lawyer. Other cases you'll have to take on their merit, and if an apparently legitimate image owner such as this does state the wrong license terms I don't think we can double-guess them. Lithopsian (talk) 17:03, 25 February 2018 (UTC)
Exactly. At the end of the day we have to do our due diligence, but if the releasing entity who is otherwise credible has screwed up their copyright (or lack thereof) claim, there's not much we can do with it. I'm a big proponent of the precautionary principle at Commons, but in situations like this we'd end up deleting a vast swath of the database if we disregard their own statements. Huntster (t @ c) 13:27, 26 February 2018 (UTC)
Just for reference, DSS (not to be confused with the entirely separate and now free-to-use SDSS) images in general are copyright. There is no question about that. I delete maybe one a week from Commons, but I suspect there are dozens or even hundreds still on there. They are widely available through apparently-free software like Aladin but are still copyright. I don't know what the mechanism is for releasing particular DSS images into the public domain as is apparently done by by institutions like STScI and ESO, but I can only assume it is legitimate. Lithopsian (talk) 17:07, 25 February 2018 (UTC)

Template:Wikidata redirect on all MP#Rs with a Wikidata item?

As Paine Ellsworth started doing, I figured I'd follow-through and place {{Wikidata redirect}} on all of our main Minor Planet #Redirects which have a Wikidata item currently associated with it (secondary/tertiary/etc. #Rs shouldn't have a WD item anyway). Yea/nay?   ~ Tom.Reding (talkdgaf)  19:00, 25 February 2018 (UTC)

Hi Tom, and thanks again for helping! I am working through Category:Redirects connected to a Wikidata item, and I have finished the "early" minor planets that are sorted there. I'm neutral on whether or not redirects should have WD items, though I don't see anything wrong with it. I'm placing the {{Wikidata redirect}} rcat on those category entries because I think it's important that editors are readily informed about it when they click on a WD redirect link. Thanks again!  Paine Ellsworth  put'r there  19:34, 25 February 2018 (UTC)
Oh I wasn't even aware of that tracking cat! I'm surprised it's so low (~2600)...and most of them aren't even MPs...   ~ Tom.Reding (talkdgaf)  21:16, 25 February 2018 (UTC)
It's worth noting that whether or not Wikidata sitelinks to redirects are good or bad is an open discussion, see d:Wikidata:Requests for comment/Allow the creation of links to redirects in Wikidata. Personally, I wouldn't spend too much time adding/removing them until that's been decided. Thanks. Mike Peel (talk) 20:09, 25 February 2018 (UTC)
Excellent! Thank you; that's relevant for many projects.   ~ Tom.Reding (talkdgaf)  21:16, 25 February 2018 (UTC)

Object type of M104?

Please see Talk:List of Messier objects#Object type of M104. Input is welcome. -- Toshio Yamaguchi 10:38, 3 March 2018 (UTC)

Deletion discussion of Spiral galaxy dynamics

Article Spiral galaxy dynamics has been nominated for deletion discussion. Editors interested in the discussion are welcome to share their views on the deletion discussion page. Thanks --UbedJunejo (talkcont) 19:10, 11 March 2018 (UTC)

Plea from a simpleton

Is there a simple red-shift-number-to-universe-age table hereabouts? If not, and it's not at Redshift, could someone create a barebones one there? The talk page comment is at Suggestion to help the simpletons. Shenme (talk) 20:43, 12 March 2018 (UTC)

It isn't fixed, so a table might be inappropriate although certainly you can find them (eg here). Hubble's law contains a list of reported values (or ranges) for the Hubble Constant that relates redshift to distance, and also has a graph that effectively shows you the relationship. Lithopsian (talk) 20:46, 12 March 2018 (UTC)

redirect to Messier's catalogue article

Hi, I have just discovered this redirect made in 2004 and it actually confused me a little bit. Am I the only one?

It is linked to the original title of the catalogue, Catalogue des nébuleuses et des amas d'étoiles, so a translation of the second half... but in my experience noone knows it like "Nebulae and Star Clusters", using only the second half of it. IMHO, it does not ring a bell when you say it like that. I found it on google although not all in the first results, but I have asked around to other people with Ph.D. and the string "Nebulae and Star Clusters" is not understood as specific of this work, so how can anyone in practice search for it or use it as a redirect here? In facts, it is unused.

Plus, at the time galaxies were considered nubulae, but not now, so without "Messier" people might be confused about the meaning of the redirect, since some Messier objects are not nebulae or star clusters, and many other clusters are not in the Messier catalogue. Some people actually were, before searching and reading and understanding that it was part of the catalog's original name. I have discovered it putting "Nebulae" in the search bar and originally I though that it was a redirect to some list of pages on the whole topic. Actually, the astronomer in my poll was more confused about it when I showed it, which is fun to think about. I could guess almost immediately there was some historical reason (the original title), he couldn't.

I am really curious: are me and my friends the only ones to feel this way? that is, to think this redirect confuses more than it helps?--Alexmar983 (talk) 22:39, 13 March 2018 (UTC)

Alexmar983, you're welcome to send it to WP:RFD if you do not think it is useful. However, being a partial match for a title of a book written by Messier is (if I remember correctly) one of the acceptable reasons to have a redirect. I could be misremembering, though. Primefac (talk) 11:30, 14 March 2018 (UTC)
Primefac I let the project decide, if people here agree, I'll link this discussion to RFD, otherwise fine with me. it's just that after having spent 20 minutes to discuss it (someone had a boring night, I guess), adding 5 minutes to write here was no big deal. Do you think it's not confusing? if so, we keep it.--Alexmar983 (talk) 11:48, 14 March 2018 (UTC)
I mean, it wouldn't be the first thing I'd be searching if I was looking for Messier Objects (or his book), but I could certainly see someone thinking "it was something about nebulae and clusters..." so I couldn't say if it's useful overall. Pageview analysis shows less than 1 hit per week for the last year, which is quite a bit lower than the 200-300 seen by the article itself. Primefac (talk) 11:59, 14 March 2018 (UTC)
I saw that number, I cut that part to reduce the size of my commment... but still the question remained in my head. Are those readers actually looking for Messier's catalog when they click there? Or are they more similar to my case, that is typing "nebulae" and clicking on it from the scroll menu thinking it is some short string for a redirect to a list of summary pages? I guess we'll never know.--Alexmar983 (talk) 13:51, 14 March 2018 (UTC)
Not the most brilliant and necessary redirect I've ever seen, but I don't find it confusing. Follow it and you get to a type of nebula or star cluster. Possibly there is a better target for it? I don't see anything that would obviously mark it out for deletion, the criteria for allowing redirects are pretty loose. Boldly retargeting is almost always better than weeks of discussion that nearly always result in ... retargeting. New General Catalogue of Nebulae and Clusters of Stars? Don't double-redirect of course. Lithopsian (talk) 17:29, 14 March 2018 (UTC)
What about Catalogue of Nebulae and Clusters of Stars too :D? I feel that what is missing (or i cannot find) is a page where all possible catalogues are listed with some comments, that it is the page I would make a redirect too, the most honest one for a reader. Not a disambiguation page, that I assume it's correct if it is string-based, but a "content page".
I am not sure if there is a clear scientific word to encompass these diverse "non star deep-sky objects" (not my real field, sorry) but in general a list with some comments of the articles listed in Category:Astronomical catalogues (and similar subcategories or same-level categories) by year of creation or main author/project could be probably useful. The perfect redirect should direct to that.
Just a guess, of course. In my experience by field and language this type of confusions can be ignored for years, but sometimes it is useful to reveal if something "structural" is missing. Look for example at Template:Messier objects or Template:Caldwell catalogue who include the objects and some historical catalogues. i believe that that second part in those navboxes should be removed in a new separate navbox, to be further enlarged and improved over the years. That could be a future base also on an article-list of some types. You see that quite well when you open Herschel_400_Catalogue that has no navbox. Just a suggestion, of course. Sorry I cannot really help... maybe I can separate the navbox, it is a good "seed" to plant.--Alexmar983 (talk) 14:55, 15 March 2018 (UTC)

Units for equatorial coordinates?

I was trying to look up the location of Orion_(constellation), and the infobox says RA=5, dec=+5. I was not familiar with the equatorial coordinate system, so I clicked through and found that both RA and dec are angles. Shouldn't we provide the units for those angles? In math, angles without units are typically taken to be in radians, but here I guess RA is in hours and dec is in degrees (correct?). The usage instructions for {{infobox constellation}} recommend to use the templates {{RA}} and {{DEC}} which add the proper units automatically. For experts, the assumed units are probably clear, but adding them won't hurt and would make things easier for laymen. Cheers, AxelBoldt (talk) 21:32, 14 March 2018 (UTC)

The correct units are hours (h) and degrees(°). I would have thought the infobox should be adding them. The documentation says those fields expect a range and should use the {{RA}} and {{DEC}} templates, which would provide the units. A spot-check suggests this isn't happening for many constellations, but is for some (eg. Pavo (constellation)). Lithopsian (talk) 21:40, 14 March 2018 (UTC)
Infobox constellation does not automatically add RA and DEC. Given that either single center coords or ranges are accepted, it wouldn't be practical for the infobox to automatically add the formatting. Huntster (t @ c) 01:26, 15 March 2018 (UTC)


Hi, I created the article K2-155d but I’m planning big improvements to the article. Today is just a start. Anything I should add in the article (if so feel free to list them down and sources I can use for each of them)? LovelyGirl7 talk 00:48, 22 March 2018 (UTC)

I suggest adding links for technical terms like habitable zone and insolation. Is there any information about the orbital eccentricity? Thanks. Praemonitus (talk) 03:35, 22 March 2018 (UTC)
@Praemonitus: I’ve wikilinked the 2 you told me. However, there isn’t really any information about its orbital eccentricity. I can’t find a source that mentions it’s orbital eccentricity, but you could let me know below for a source mentioning it as well as the link for it. Anything else I can add to the article to continue improving it? —LovelyGirl7 talk 11:56, 22 March 2018 (UTC)
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