Talk:Bortle scale

Colour key
Is there an official correspondence between the Bortle scale and the colour key? The article's colours are split in a slightly different fashion from the Northern Virginia Astronomy Club colour scheme found in the External Links section. Bortle's article in Sky & Telescope doesn't mention colours. As far as I can tell, what everyone's trying to do is to match his 9-point scale to the light pollution maps on the World Atlas of Artificial Night Sky Brightness (also in Ext. Links), which has only 8 colour gradations -- so of course the two scales don't quite match up. Considering that the World Atlas dates from 2000 and Bortle's article appeared in 2001, I don't think the Atlas was created with Bortle's scale in mind. 98.199.232.32 (talk) 06:55, 26 May 2011 (UTC)
 * Sorry, never mind. Second paragraph in the article. Reading comprehension fail. 98.199.232.32 (talk) 03:06, 27 May 2011 (UTC)

SQM
Anyone know the relationship between Bortle and Sky Quality Meter (SQM) which measures in mag/arcsec2? --Chuunen Baka (talk  • contribs) 12:23, 16 October 2012 (UTC)

The whole question of a standardised, objective methodology for assessing sky quality (darkness) remains an unresolved one. SQM, like any digital device, gives a numerical output, but there are assurances only about "precision", and nothing about "accuracy." This should be a source of caution, if not concern.

The Bortle scale suffers from many difficulties; very low, possibly unattainable visual magnitudes, underestimation of cloud illumination from distant sources (high clouds can give more LP over a wider area than low ones, for example.)

So, in looking at this whole question, it's obvious that a standardised, calibrated and reliable method that can be repeated 100 years in the future with no problem, simply doesn't exist. — Preceding unsigned comment added by 185.20.131.196 (talk) 08:24, 28 November 2014 (UTC)

Requested move 1

 * The following discussion is an archived discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review. No further edits should be made to this section. 

The result of the move request was: not moved, for the moment. We generally do allow the proposed title to be changed mid-RM but it often creates a bit of a mess for closers. So I'm closing this RM but would recommend that a new one be started up as soon as Dicklyon is ready, with "Bortle scale" as the proposed title. Jenks24 (talk) 12:31, 4 April 2013 (UTC)

Bortle Dark-Sky Scale → Bortle dark-sky scale – per MOS:CAPS, caps are not necessary; not a proper name; many reliable sources use lowercase. Dicklyon (talk) 02:41, 25 March 2013 (UTC)
 * Oppose this appears to be a proper name. The only source in the article for this particular scale is the official website. What sources are you seeing lowercase? -- 65.92.180.137 (talk) 07:11, 29 March 2013 (UTC)
 * Oppose. As with anon, I'm not seeing what you're seeing. A quick G-search shows an almost 10-1 usage as a proper noun. IMO lowercase would only be appropriate when referring to it as "John Bortle's dark-sky scale". — Huntster (t @ c) 10:07, 29 March 2013 (UTC)
 * There are not a ton of uses in secondary sources, and most are in titles, headings, or references to the author's primary-source title "Introducing the Bortle Dark-Sky Scale", none of which have much to say about how to capitalize it. Some books do use it in lower case: , .  Some sources lower-case the article title reference , and refer to the scale as the "Bortle scale".  Others use "John Bortle's dark sky scale". Many just call it the "Bortle scale" (some with "Bortle Scale").  And some "Bortle Scale of Light Pollution".  There's very little evidence that this should be treated as a proper name; it's just a scale named for a guy.   Probably a better title suggestion would have been "Bortle scale", yes?  Dicklyon (talk) 06:12, 4 April 2013 (UTC)
 * Books are also big on "Bortle scale". Can I revise my proposal?  Dicklyon (talk) 06:16, 4 April 2013 (UTC)
 * The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.

Requested move 2

 * The following discussion is an archived discussion of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section. 

The result of the proposal was moved. --BDD (talk) 20:32, 30 April 2013 (UTC)

Bortle Dark-Sky Scale → Bortle scale – Per the closing advice of the first RM above, I've revising the proposed new name and starting a new RM. This scale is widely referred to by various names, including very commonly "Bortle scale". A large number of the instances of "Bortle Dark-Sky Scale" in books are references to Bortle's paper title "Introducing the Bortle Dark-Sky Scale", which is usually but not always capitalized. Based on the diversity of things it's called, and lowercasing, there's little evidence that there's a proper name here. Might as well go with the concise generic term used in about 50 books. With wiki-mirror books excluded, few books use the full expression. Relisted. &mdash;Darkwind (talk) 01:14, 23 April 2013 (UTC) Dicklyon (talk) 16:36, 4 April 2013 (UTC)


 * Oppose I prefer the current title over the shorter less defining "Bortle [S/s]cale"; though wouldn't mind John Bortle's dark sky scale of light pollution, as a descriptive title instead of prescriptive title. -- 65.92.180.137 (talk) 05:05, 6 April 2013 (UTC)
 * "Bortle's dark-sky scale" would be a commonly used alternative that's usually lowercased, sensibly punctuated, and concise yet descriptive. Go there?  Dicklyon (talk) 05:32, 6 April 2013 (UTC)


 * Support. With a redirect from the present title? Sounds good to me. What's to mind? Hertz1888 (talk) 07:23, 6 April 2013 (UTC)
 * Well, the last time I suggested a revision of the proposed new name, my RM got closed and I had to start over. Maybe we can some more opinions here and settle this without starting over this time?  In any case, the present over-capitalized version is not supportable per MOS:CAPS.  Dicklyon (talk) 19:20, 6 April 2013 (UTC)


 * Support move. Seems to be a common name with the benefit of simplicity. Unless someone can demonstrate that Bortle created other scales within the field, there is little to disambiguate. --  Ohconfucius  ping / poke 04:01, 23 April 2013 (UTC)
 * The above discussion is preserved as an archive of the proposal. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

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The SQM column is way off
Where I live, rural skies are something like 21.4 SQM, and dark sky sites at national parks only surpass 21.7 if it's exceptionally transparent (as measured by my SQM-L device). The current SQM ranges don't match up with the cited Nomogram. — Preceding unsigned comment added by 174.116.183.78 (talk) 20:36, 25 May 2022 (UTC)


 * Average (or is it median?) unpolluted sea level cloudless full night is about 21.6 at the zenith or 80 nanolamberts, at least with no aurora, the same thing at solar minimum is about 60 nanolamberts. Sagittarian Milky Way (talk) 22:04, 25 May 2022 (UTC)

Bortle 1 SQM discussion
I recommend changing the Bortle 1 SQM column from 21.75 - 22 to > 21.75. I have measured sqm fainter than 22 on exceptional nights, including not at the zenith. DrRogerNClark (talk) 19:22, 7 June 2023 (UTC)

zodiacal light & zodiacal band bullet points
I quickly added a link in Bortle Class 1 to point the bullet item "zodiacal band" to "zodiacal light".

I then wondered if those two bullet points, the 1st and 3rd, (zodiacal light and zodiacal band) should be merged into a single bullet like "the zodiacal band and the zodiacal light is visible and colorful"

I would have made this change, but wanted to ask if this is something agreeable, or if they do need to be two points as is, or there is a better way to phrase a single bullet point similar to my example. AreThree (talk) 23:51, 2 January 2024 (UTC)