explain xkcd - User contributions [en]

3164: Metric Tip

2025-11-06T00:50:09Z

82.132.246.185: /* Explanation */

{{comic
| number = 3164
| date = November 5, 2025
| title = Metric Tip
| image = metric_tip_2x.png
| imagesize = 187x322px
| noexpand = true
| titletext = The package weighs 7 kg 9 oz.
}}

==Explanation==
{{incomplete|This page was created by a 6 LB, 243 g ROBOT. Don't remove this notice too soon.}}
This comic parodies the common advice for people converting between one system of measurement and another, which is to 'do it in steps'. In this case, instead of doing it normally (i.e converting the entire measurement to metric and then saying the conversion), Cueball's response is to give the first part of the measurement in the {{w|Imperial units|Imperial system}} (or the practically equivalent {{w|United States customary units}}), and then give the second part in {{w|Metric system|metric}}. This is worse than saying it all in one single system, as it is much more awkward and much more confusing for the receiver.

The title text gives another example of Cueball's conversion system, in which he gives the weight (or {{w|Weight#Mass|''perhaps'' mass}}) of a package as being seven kilograms and nine ounces, converting between metric and imperial partway through the message (rather than starting with imperial and ending with metric). However, this is [[technically]] worse, as kilograms are strictly a unit of mass whereas ounces ''can'' be a unit of mass but are usually effectively {{w|Ounce#Definitions|one or other}} measurement of weight ''or'' (in line with popular US usage) a {{w|Fluid ounce|volume}} measurement.

This is also the first comic to give a height for Cueball, at 5'9" (176 cm).

==Transcript==
:[White Hat and Cueball are standing and facing each other.]

:White Hat: How tall are you?
:Cueball: 5ft 24cm

:[Caption below the panel:]
:When switching to metric, make the process easier by doing it in steps.

{{comic discussion}}<noinclude>
[[Category:Comics featuring White Hat]]
[[Category:Comics featuring Cueball]]
[[Category:Tips]]

Template talk:comic

2025-11-06T00:15:23Z

82.132.246.185: /* Extra Page vs Extra Comic */

==First and last?==
How about adding links to [[1]] and [[{{LATESTCOMIC}}|LATESTCOMIC]] (with graphics matching xkcd's |> and <| perhaps)? [[User:J-beda|J-beda]] ([[User talk:J-beda|talk]]) 13:11, 8 September 2012 (UTC)

==Imagesize==
Can we kill imagesize, please? We almost never use it, and we have alternatives, like using the smaller "thumbnails" that you click through on the xkcd site as the images that we store. It'll let us link the image to the xkcd site too. [[User:Davidy22|Davidy22]][[User talk:Davidy22|<tt>(talk)</tt>]] 01:29, 27 November 2012 (UTC)

:Have faith that eventually the image bug will be resolved! It probably won't but we can all dream. [[User:Lcarsos|lcarsos]]_a ([[User talk:Lcarsos|talk]]) 02:27, 27 November 2012 (UTC)

::I just had a massive brainwave. We don't actually need to include imagesize if we're going to leave it empty. Since it's a named option we can specify any order of options, and omit those we don't need to use. I'm going to edit {{tl|create}} (if I can figure it out to not include imagesize so it will just be an advanced user's option. Hopefully that will make you smile, in these dull days of spam fighting. [[User:Lcarsos|lcarsos]]_a ([[User talk:Lcarsos|talk]]) 22:15, 5 December 2012 (UTC)
==Radiation et al==
I had some spare time today so I went and made a modified version of this template that can handle undefined numbers such as in [[Radiation]]. Only catch is that it needs two other variables to be defined to keep the link valid... But I think that's a fair compromise to take another page off the incomplete explanations category. It could also allow for the addition of pages about the not-so-subtle jokes etc. in the what if series. The updated versions are over at [[User:Pixali/comictemplate/|a page in my userspace]] and [[User_talk:Pixali/comictemplate/|its talk page]]. [[User:Pixali|Pixali]] 02:07, 4 March 2015 (UTC)

== Broken? ==

On unnumbered comics, this template displays "<nowiki>[[Expression error: Unrecognised punctuation character "{".|Next >]]</nowiki>". {{User:17jiangz1/signature|07:54, 27 August 2015}}
:A user someplace made a workaround in a seperate template. I'll find it later. '''[[User:Davidy22|{{Color|#707|David}}y²²]]'''[[User talk:Davidy22|<tt>[talk]</tt>]] 08:03, 27 August 2015 (UTC)
:{{done}} - It was because [[0]] was created, so the logic that #ifexist:0 should be false failed. I changed it to default to -2 when number is not present, which will work as long as no one creates [[-1]]! [[User:Markhurd|Mark Hurd]] ([[User talk:Markhurd|talk]]) 11:13, 14 September 2015 (UTC)

== Use https? ==

XKCD has supported https for a while, it might be a good idea to switch the generated links to https.

[[User:Kenzierocks|Kenzierocks]] ([[User talk:Kenzierocks|talk]]) 17:38, 20 October 2016 (UTC) kenzierocks
:Done. '''[[User:Davidy22|{{Color|#707|David}}y²²]]'''[[User talk:Davidy22|<tt>[talk]</tt>]] 18:00, 20 October 2016 (UTC)

:: And [http://www.explainxkcd.com/wiki/index.php?title=Template:comic&diff=135097&oldid=128889 reverted], apparently – why? --[[Special:Contributions/162.158.114.40|162.158.114.40]] 15:29, 7 January 2018 (UTC)
:::{{Done}} That's fixed now. --[[User:FaviFake|FaviFake]] ([[User talk:FaviFake|talk]]) 09:10, 26 April 2025 (UTC)

== The template field called "titletext" ==

=== Bad choice for the "displayed name" of this ["titletext"] field ===

As a general rule, I DO like the idea of using the same character string, that is the name of a certain field in a given template, as the "displayed name" -- that is, what the user [[sees]] when the '''value''' of that field is being displayed.

'''However,''' in this case, the field that is [now] called the "titletext" field, is an exception to that general rule.

The "titletext" field is used to show (and maybe also to help "explain"?) the contents of a little pop-up with some "caption" or other text, that appears when one "hovers" his [[mouse]] over a certain XKCD cartoon.

I do not know why the field name "titletext" was chosen.

Some might even want to suggest, changing the spelling of the field name "titletext".

That might be ("also") an interesting debate ... but that is outside the scope of "[[my]]" comment today.

[[IMHO]] the character string "titletext" -- or even "title text" [two words] -- would '''NOT''' be a good choice for the "display name" of the field that is used for the contents of that little pop-up with some text that appears (it "pops up") when one "hovers" his [[mouse]] over a certain XKCD cartoon.

True, it does usually contain some ["caption" or other]'''"text";''' so, the [[second half]] of that field name is not [absolutely] a misnomer. But ... the [[first]] half of that field name '''is''' a misnomer. It is NOT [anything LIKE] a "title"!

=== A "title" IS *** [[SHORT]] *** ! ===

The *** [[title]] *** of a book (or magazine article) is '''NOT''' something that requires more BYTES to represent (or display) it, than the entire book or magazine article. It is SHORT.

This field (called "titletext") might '''''sometimes''''' be short ... but not very often. For the most recent XKCD I looked at, it (the pop-up "upon mouse hovering" text) contained MORE text than the entire XKCD cartoon over which my mouse was "hovering" when it [the value of this field] was being displayed as a pop-up. (''Including'' [[dialog]], "if any".)

So, I don't know what the "displayed name" of this ["titletext"] field should be. Nominations would be welcomed. But, IMHO, I do not vote for displaying it as [something like] "title text". IMHO, that is worse than [just] "unhelpful" ... it is actually '''confusing'''.

Any comments? Thanks! [[User:Mike Schwartz|Mike Schwartz]] ([[User talk:Mike Schwartz|talk]]) 19:02, 13 April 2017 (UTC)

== HTTPS again ==

The template could link to the HTTPS version of xkcd. It seems like this was requested before, but reverted.

Also, while you're at it, the "www." in the link is superfluous and could also be removed.

-- [[Special:Contributions/162.158.114.58|162.158.114.58]] 11:40, 19 September 2018 (UTC)
:I don't know why it was reverted, but I think this is a minor issue because every http request is always redirected to a secure connection. This means I will change it back to https. But because I'm an old fashioned guy and we are using the WorldWideWeb the www remains. --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 18:44, 19 September 2018 (UTC)

:::{{Done|Fixed}} both the unnecessary www and the nowrap of the button. --[[User:FaviFake|FaviFake]] ([[User talk:FaviFake|talk]]) 09:15, 26 April 2025 (UTC)

== Wordrapping and Ordered list buttons ==

I would propose that the text of each of the "buttons" be put in a style where word-wrap is disabled. As is, on my smaller screens, the back button always word-wraps between the "|" and the "<". I believe adding a style attribute with "white-space: nowrap" to each item of the unordered list (<li>) would fix this.

Alternatively, adding the style attribute it to the whole list (<ol>) would keep the whole thing from word-wrapping.
-- Previous comment was by [[User:Trlkly]]

:Yup, this would also fix this bug:
::[[File:navigation broken CSS.jpg|300px]]
:which has been observed in at least the latest comic today. --[[User:NeatNit|NeatNit]] ([[User talk:NeatNit|talk]]) 18:22, 8 December 2019 (UTC)
::{{Done}} I fixed it. --[[User:FaviFake|FaviFake]] ([[User talk:FaviFake|talk]]) 09:08, 26 April 2025 (UTC)

== Broken link ==

At [[Blue Eyes]], the button "Comic (October 11, 2006)" links to https://xkcd.com/blue_eyes.html/ and shows a 404 Not Found error message, however, the comic is at https://xkcd.com/blue_eyes.html, without the slash at the end. Can someone fix this? [[User:ObserveOwl|ObserveOwl]] ([[User talk:ObserveOwl|talk]]) 19:29, 7 July 2021 (UTC)
:I did fix it a long time ago by adding a # at the end of the link in the template --[[User:FaviFake|FaviFake]] ([[User talk:FaviFake|talk]]) 16:13, 3 November 2024 (UTC)
::{{Done}} Now I fixed it properly so we don't need a workaround. --[[User:FaviFake|FaviFake]] ([[User talk:FaviFake|talk]]) 08:35, 23 March 2025 (UTC)

== add default class name to "bodyclass" input ==

For some reason, this template has a bodyclass input that, to my knowledge, is not used on any page whatsoever. If this is changed to a fixed class name, or even a defualt one, it would allow for much more intuitive changes for users that wish to use custom CSS for the wiki. [[User:SomeoneIGuess|someone, i guess]] ([[User talk:SomeoneIGuess|talk]])

== Title or Alt? ==

I think the "Title text" should be replaced by "Title/Alt text" --[[User:Bb777|hi]] ([[User talk:Bb777|talk]]) 00:38, 24 March 2025 (UTC)
:Title text is the correct word, see [[Title text]]. --[[User:FaviFake|FaviFake]] ([[User talk:FaviFake|talk]]) 16:18, 24 March 2025 (UTC)

== Random button should link to Special:RandomInCategory ==

currently the random button at the bottom center can go to ''any'' page, not just comic explanations. it should link to [[Special:RandomInCategory/All comics]]. also for earlier comics there is no random button which is kind of annoying if you are repeatedly randoming (which is the way i usually consume xkcds) —[[Special:Contributions/172.70.207.34|172.70.207.34]] 07:06, 26 April 2025 (UTC)

:I agree it's not perfect, but if it linked to [[Special:RandomInCategory/All comics]], then the extra comics wouldn't be in the pool and would never show up. Also, I din't think about the second point, you're right. Where should I place the button on the OG comics? I can't think of a good spot. --[[User:FaviFake|FaviFake]] ([[User talk:FaviFake|talk]]) 10:50, 26 April 2025 (UTC)

:I also had this problem, I think it makes more sense to change it because on xkcd the random button only points to comics that are actually published. If someone wants to see other pages they can use the random button in the sidebar on this wiki or just go searching through the categories. In reply to adding a random button to the original comics, why not include two bottom bars? The grey one can be used on all of the comics and the white one can go below that for the original comics. [[Special:Contributions/172.71.147.27|172.71.147.27]] 18:20, 27 April 2025 (UTC)

::I don't like the idea of two bars. If there are two at the bottom, then there should be two at the top too, and we get to 4 total navbars, which isn't pretty or user-friendly.

::''> on xkcd the random button only points to comics that are actually published

::Well, on xkcd the deleted or extra comics aren't available or explained. --[[User:FaviFake|FaviFake]] ([[User talk:FaviFake|talk]]) 08:28, 2 May 2025 (UTC)

:::Does anyone here know how to create a random link that fetches pages from two different categories? --[[User:FaviFake|FaviFake]] ([[User talk:FaviFake|talk]]) 10:12, 4 May 2025 (UTC)

:::That makes sense, but would it be possible to limit the random button to just ''comics'' because, as of now, the button might also take you to categories or user pages which isn't desirable. In addition could the extra comics have a bottom bar with a random button? (As of now extra comics just have a top bar with the comic name and no other buttons. It would be nice if they had a random button on the bottom as well.) I personally think three bars on the original comics wouldn't look too weird but I respect your opinion. [[Special:Contributions/172.71.142.80|172.71.142.80]] 17:20, 4 May 2025 (UTC) (Same person as 172.71.147.27 but on a different wifi network)

::::> ''[...] would it be possible to limit the random button to just ''comics'' [...]
::::Yup that's what I was wondering. I asked this in the Technical portal. FYI, you can always go to a random page even in the OG comics by clicking the link in the left sidebar. --[[User:FaviFake|FaviFake]] ([[User talk:FaviFake|talk]]) 14:40, 5 May 2025 (UTC)
:::::{{Done|Fixed the non-comic pages}} appearing. I used a new category: [[:Category:All pages]]:
:::::: {{:Category:All pages}}
:::::The other issue is still not fixed. --[[User:FaviFake|FaviFake]] ([[User talk:FaviFake|talk]]) 13:35, 11 May 2025 (UTC)

== Extra Page vs Extra Comic ==

Can someone add a boolean value extrapage and change the current extra to extracomic to differentiate extra pages on xkcd and extra comics, as suggested on {{diff|390212|the proposals portal?}} '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 22:16, 5 November 2025 (UTC)
:Additionally, the button "Go to comic" should be changed to "Go to page" if extrapage = yes. '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 22:33, 5 November 2025 (UTC)
:It's not a boolean value, it's (currently) a text value that can be "yes", anything else is 'not yes'.
:The current bit you need to look at is where the "Don't try to categorise the Main Page nor the extra comics" intro is.
:To deconstruct it:
<nowiki>{{#ifeq: </nowiki>** Compare
<nowiki> {{FULLPAGENAME}} </nowiki> * the page rendered
<nowiki> | </nowiki>** with
<nowiki> {{int:mainpage}} </nowiki> * the mainpage identity
<nowiki> | </nowiki>** if it IS that, then
<nowiki> </nowiki> * do nothing
<nowiki> | </nowiki>** else
<nowiki> {{#ifeq: </nowiki> ** a new compare of
<nowiki> {{{extra|}}} </nowiki> * "extra=" , if exists
<nowiki> | </nowiki> ** with
<nowiki> yes </nowiki> * the word "yes"
<nowiki> | </nowiki> ** if was "extra=yes"
<nowiki> [[Category:Extra comics]]</nowiki> * add one category
<nowiki> [[Category:All pages]] </nowiki> * and another
<nowiki> | </nowiki> ** else
<nowiki> </nowiki> * ...
<nowiki> </nowiki> * 'normal' comic things

:To make different "extra=foo" functions, change the "yes" match-text accordingly.
:To add "extra=bar" (or "somethingelse=bar") check, go to the "else...'normal' comic things" spot and add a further <code><nowiki>{{#ifeq: X | isY | doXisY | ...elsedo... }}</nowiki></code> but. You'll need to make sure the closing <nowiki>}}</nowiki> is added at the proper place after the "'normal' comic things" to close this new level of if-then-elsing.
:I still suggest you ''ifeq extra=comic ...as above...'' and then ''ifeq extra=page ...as per Cat:Extra Pages handling...''. And then you'd perhaps need to unHotCat the hardcoded category memberships once its handled via Template implementation.
:Actually, I suggest perhaps someone like FaviFake, or another regular who has already dealt with this spaghetti-code before, looks at it/edits it. If I could edit it, I'd still want to check that others like them agreed with my suggested changes/inserts, just because other people might need to understand the spaghetti in the future.
:This ''is'' all potentially complex, which can be a problem without having your head around what this scripting does in the first place. I've done my best to try to shown what happens/needs to happen, but it's difficult to be sure I'm aiming at a useful level of explanation when I'm not able to do this in person and perhaps with you fiddling with a testbed. [[Special:Contributions/82.132.246.185|82.132.246.185]] 00:15, 6 November 2025 (UTC)

3146: Fantastic Four

2025-11-05T23:01:30Z

82.132.246.185: /* Explanation */ more optimal wikilinks

{{comic
| number = 3146
| date = September 24, 2025
| title = Fantastic Four
| image = fantastic_four_2x.png
| imagesize = 343x388px
| noexpand = true
| titletext = One perk of being born at 0.88c is that your birthday is over two days long.
}}

==Explanation==
{{incomplete|Also, explain why Oberth effect is related }}

The comic is a pun on the {{w|Oberth effect}}, which causes orbital maneuvers to be more efficient when deep into a gravitational well.
The movie referenced is ''{{w|The Fantastic Four: First Steps}}'', released in 2025. The comic says that there is a boost because of the propulsion produced by the baby (a 'birth', rather than a 'berth'). In the movie, they do indeed go around a black hole, and she does give birth to a baby while on board, but doesn't do that to get a boost.

This effect is probably zero, as the change in the centre of mass of the ship and crew would not constitute a form of effective reaction-based propulsion.{{cn}} 

The title text states that being born at 88% the speed of light results in a birthday that's over two days long. This is due to {{w|time dilation}}: from the perspective of Earth, at 0.88 c, the dilation factor (γ) is 2.1. So one day is 2.1 days seen from Earth. The day of one's birthday has many perks, such as celebrations.

The Oberth effect was also mentioned as a key to escaping Origin in [[2765: Escape Speed]].

==Transcript==
:[Ponytail is facing Cueball with one of her hands out, facing up and towards Cueball.]
:Ponytail: In the new ''Fantastic Four'' movie, their ship doesn't have enough fuel to get home and Sue Storm goes into labor, so they slingshot around a neutron star and fire their engines at periapsis — as Sue has her baby — to get a boost.
:Cueball: Ah yes, the Obirth effect.
{{comic discussion}}<noinclude>

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Movies]]
[[Category:Physics]]

Talk:3156: Planetary Rings

2025-11-05T19:49:46Z

82.132.246.185:

Is my draft right? It's hard to understand a comic that hasn't yet got an explanation! [[User:RadiantRainwing|RadiantRainwing]] ([[User talk:RadiantRainwing|talk]]) 16:21, 17 October 2025 (UTC)
:I came here to say this is one of those xkcds that really doesn't need explaining. I do like the bit about "although it's theorized that [Earth] may have had [a natural planetary ring system] in the past," it's additional information I wouldn't think about just reading the panel. [[Special:Contributions/64.201.132.210|64.201.132.210]] 17:48, 17 October 2025 (UTC)
:I think you did a good job, you gave depth to the terms used, added related facts, and included comparisons netween the listed rings. [[Special:Contributions/64.114.211.102|64.114.211.102]] 18:17, 17 October 2025 (UTC)
Can't wait until our ring evolves via kessler syndrome. [[Special:Contributions/64.114.211.102|64.114.211.102]] 18:17, 17 October 2025 (UTC)
: I can't wait for the stage after that: [[2314|Carcinization]]. [[Special:Contributions/149.22.90.216|149.22.90.216]] 23:10, 17 October 2025 (UTC)

I added two notes, but I don't have time now to learn the syntax to make proper notes, so they are just in the middle of the text. I will try to do it later, if someone else doesn't do it. [[User:Rps|Rps]] ([[User talk:Rps|talk]]) 18:33, 17 October 2025 (UTC)

Earth's historical rings: {{w|Rings of Earth}} [[Special:Contributions/191.101.157.126|191.101.157.126]] 19:20, 17 October 2025 (UTC)

Mars also has a ring, although it consists of just 2 very large objects. [[User:SDSpivey|SDSpivey]] ([[User talk:SDSpivey|talk]]) 21:43, 17 October 2025 (UTC)
: Nope. Mars has TWO rings. Deimos orbits at three times the distance and four times the period of Phobos. Two rings with one large object each. And if you are taking an areocentric perspective, there's a much more massive ring 1.5 AU away. [[Special:Contributions/181.214.218.33|181.214.218.33]] 22:46, 17 October 2025 (UTC)

Regarding the title text: One of those bits of information that aids navigation has long been where on a tree the moss grows (should you be in an area with trees, obviously, and otherwise be without a compass or can see the Sun to do the watch-dial trick (with an analogue watch, or a bit of imagination)). Back in the '90s, I noted that I could augment that, in an urban environment, from the rise in houses having satellite dishes (BSB 'squarials' and Sky dishes, originally, here in the UK) all pointing pretty much directly south. (With enough local knowledge, you might even be able to compare them to TV aerials and possibly triangulate to where you were within a larger urban area - assuming you were 'somewhat lost, but not ''totally'' lost'.) And, even today, I find them a reassuring extra bit of info when I'm skirting through the suburbs of cities, knowing that I'm not being twisted too far awa from my chosen direction (working with my in-head memory of the map I'd planned with, which can occasionally get nudged off from reality by an inconvenient twist and turn of road). 
Though I must say, I've never ever considered latitude-enumeration as an additional factor. Apart from anything else, the design of the dish normally has the 'receiver arm' sitting at an off-axis focal point, so you need to project out at the complimentary 'up-angle' from the exact angle the dish itself ''points''. But, anyway, I'm not sure I ever could have distinguished 55°N from 60°N, by eye, even sighting upon a centre-axis dish's direction. And yet I'd surely already know if I was as far south as Edinburgh or actually somewhere as far north as Lerwick, before checking out the local dishes... ;) [[Special:Contributions/2.98.65.8|2.98.65.8]] 21:48, 17 October 2025 (UTC)

I don't understand why it says "If some of them are pointing straight up, you're probably near the Equator". Surely, if you're on Earth, they're pointing straight down. {{unsigned ip|86.20.197.254|18:12, 18 October 2025}}
: Well, the satellite dishes need to point up to get signal from up there in the sky. [[User:MinersHavenM43|MinersHavenM43]] ([[User talk:MinersHavenM43|talk]]) 18:17, 18 October 2025 (UTC)
: Sounds like 86...254 thinks "satellite dishes" are the transmitting/transceiving dishes ''upon'' the satellites, not the receiving/transceiving dishes aimed ''at'' them. [[Special:Contributions/2.98.65.8|2.98.65.8]] 18:40, 18 October 2025 (UTC)

Sidenote: I visited my local thrift store and found three nearly new copies of "what if?" on the Humor bookshelves. I bought one (Sorry you won't get paid twice.) and moved one to the Reference bookshelves. [[User:These Are Not The Comments You Are Looking For|These Are Not The Comments You Are Looking For]] ([[User talk:These Are Not The Comments You Are Looking For|talk]]) 20:21, 19 October 2025 (UTC)

I accidentally nerdsniped myself by asking "How many geostationary satellites would we need to have a ring visible from the moon?". I don't even know where to begin with it. Google's AI said it's between 80 million and 540 million (based on the brightness of a single satellite and the lowest brightness visible to the naked eye), but I'm hesitant to trust LLM generated math. Someone please help! [[User:Stroopwafel Falafel|Stroopwafel Falafel]] ([[User talk:Stroopwafel Falafel|talk]]) 18:16, 5 November 2025 (UTC)
:A single metre, at the distance from the Moon to GEO seems like it would subtend ~5.9x105 arcminutes of angle(near-side) to ~4.9x105 (far-side), give or take a little adjustment for exact viewpoint.
:Visual acuity is variously quoted as between a few arcseconds and about an arcminute, but that's more distinguishing one thing at one point in vision from another ''nearly'' at that point in it. Pinpricks of light distinguish themselves out from a background, of course. But it looks like that Venus is (optimally) from roughly 105,000 to 125,000 times as wide, or square those numbers for the ratio of solid angles, so we'd be talking about the level of far fainter stars.
:I think that (as specs of light, spread out) you don't ''necessarily'' need even a million of them, but it would be a tenuously-visible definable hairlike feature at best if you put m² 'blocks' edge-to-edge in an 'arc structure'. (Also, if you connected them, wouldn't the 'orbital Centre Of Gravity' be somewhere half way along the chord between the two ends, changing the orbital period it wants to drift round at, or does the non-Newtonian rotating frame of reference let it sit on the 'mid-block' of the arc? Before considering gravitational pull ''between'' the blocks, of course.)
:But it'd be a 'whisp'. Perhaps folding out to tennis-court size (or larger), plus relying on the perfect orientation for visible reflection from their surface would help. You could leave them drifting hundreds of metres apart, or further, each point notable more for being part of a linear 'asterism' of faint points (like a more compact Milky Way effect), getting away with fewer.
:So are we talking of enough satellites to be 'large enough and close enough' to make such a whisp (at near/far extremes) and then extrapolating to what this linear density means a fully-filled orbit would need? (Rather than bunches of them, suggesting the whole orbit only by a 'dashed line', each dash made up of dots.)
:Looking at it from the other side, the ''width'' of GEO, seen from the Moon, would be about 10-degrees of arc (very visible, assuming the points of the arc are). Theoretically 224 million "metre-cubes" elbow-to-elbow would fill it... in a (thinner-than-)hair-thin structure, but those tennis courts (or, lets get ambitious, football-field sized... ''any'' kind of football, but perhaps Aussie Rules would be a useful aspiration), all at handy Sun-reflecting angles..? They could be less dense, far from touching. Be creative with geosynchronous-but-not-geostationary orbital constellations, and it'd thicken-up that hairline feature (at the expense of the satellites needed maybe being a simple multiple, to deal with off-equatorial dispersion of 'density').
:I'm most worried about the need to individually control each flat reflector to make best visible to a given Moon-observer, though. Feel free to recalculate for (say) silvered spherical 'inflatable' satellites, or something, of some size ''probably'' nowhere near that of a sporting arena. But we definitely need to know more about the albedo-/reflecti ity-profile of whatever we try to spatter around the orbit, before we can tie down everything else about the problem. [[Special:Contributions/82.132.246.185|82.132.246.185]] 19:49, 5 November 2025 (UTC)

Talk:3156: Planetary Rings

2025-11-05T19:49:05Z

82.132.246.185:

Is my draft right? It's hard to understand a comic that hasn't yet got an explanation! [[User:RadiantRainwing|RadiantRainwing]] ([[User talk:RadiantRainwing|talk]]) 16:21, 17 October 2025 (UTC)
:I came here to say this is one of those xkcds that really doesn't need explaining. I do like the bit about "although it's theorized that [Earth] may have had [a natural planetary ring system] in the past," it's additional information I wouldn't think about just reading the panel. [[Special:Contributions/64.201.132.210|64.201.132.210]] 17:48, 17 October 2025 (UTC)
:I think you did a good job, you gave depth to the terms used, added related facts, and included comparisons netween the listed rings. [[Special:Contributions/64.114.211.102|64.114.211.102]] 18:17, 17 October 2025 (UTC)
Can't wait until our ring evolves via kessler syndrome. [[Special:Contributions/64.114.211.102|64.114.211.102]] 18:17, 17 October 2025 (UTC)
: I can't wait for the stage after that: [[2314|Carcinization]]. [[Special:Contributions/149.22.90.216|149.22.90.216]] 23:10, 17 October 2025 (UTC)

I added two notes, but I don't have time now to learn the syntax to make proper notes, so they are just in the middle of the text. I will try to do it later, if someone else doesn't do it. [[User:Rps|Rps]] ([[User talk:Rps|talk]]) 18:33, 17 October 2025 (UTC)

Earth's historical rings: {{w|Rings of Earth}} [[Special:Contributions/191.101.157.126|191.101.157.126]] 19:20, 17 October 2025 (UTC)

Mars also has a ring, although it consists of just 2 very large objects. [[User:SDSpivey|SDSpivey]] ([[User talk:SDSpivey|talk]]) 21:43, 17 October 2025 (UTC)
: Nope. Mars has TWO rings. Deimos orbits at three times the distance and four times the period of Phobos. Two rings with one large object each. And if you are taking an areocentric perspective, there's a much more massive ring 1.5 AU away. [[Special:Contributions/181.214.218.33|181.214.218.33]] 22:46, 17 October 2025 (UTC)

Regarding the title text: One of those bits of information that aids navigation has long been where on a tree the moss grows (should you be in an area with trees, obviously, and otherwise be without a compass or can see the Sun to do the watch-dial trick (with an analogue watch, or a bit of imagination)). Back in the '90s, I noted that I could augment that, in an urban environment, from the rise in houses having satellite dishes (BSB 'squarials' and Sky dishes, originally, here in the UK) all pointing pretty much directly south. (With enough local knowledge, you might even be able to compare them to TV aerials and possibly triangulate to where you were within a larger urban area - assuming you were 'somewhat lost, but not ''totally'' lost'.) And, even today, I find them a reassuring extra bit of info when I'm skirting through the suburbs of cities, knowing that I'm not being twisted too far awa from my chosen direction (working with my in-head memory of the map I'd planned with, which can occasionally get nudged off from reality by an inconvenient twist and turn of road). 
Though I must say, I've never ever considered latitude-enumeration as an additional factor. Apart from anything else, the design of the dish normally has the 'receiver arm' sitting at an off-axis focal point, so you need to project out at the complimentary 'up-angle' from the exact angle the dish itself ''points''. But, anyway, I'm not sure I ever could have distinguished 55°N from 60°N, by eye, even sighting upon a centre-axis dish's direction. And yet I'd surely already know if I was as far south as Edinburgh or actually somewhere as far north as Lerwick, before checking out the local dishes... ;) [[Special:Contributions/2.98.65.8|2.98.65.8]] 21:48, 17 October 2025 (UTC)

I don't understand why it says "If some of them are pointing straight up, you're probably near the Equator". Surely, if you're on Earth, they're pointing straight down. {{unsigned ip|86.20.197.254|18:12, 18 October 2025}}
: Well, the satellite dishes need to point up to get signal from up there in the sky. [[User:MinersHavenM43|MinersHavenM43]] ([[User talk:MinersHavenM43|talk]]) 18:17, 18 October 2025 (UTC)
: Sounds like 86...254 thinks "satellite dishes" are the transmitting/transceiving dishes ''upon'' the satellites, not the receiving/transceiving dishes aimed ''at'' them. [[Special:Contributions/2.98.65.8|2.98.65.8]] 18:40, 18 October 2025 (UTC)

Sidenote: I visited my local thrift store and found three nearly new copies of "what if?" on the Humor bookshelves. I bought one (Sorry you won't get paid twice.) and moved one to the Reference bookshelves. [[User:These Are Not The Comments You Are Looking For|These Are Not The Comments You Are Looking For]] ([[User talk:These Are Not The Comments You Are Looking For|talk]]) 20:21, 19 October 2025 (UTC)

I accidentally nerdsniped myself by asking "How many geostationary satellites would we need to have a ring visible from the moon?". I don't even know where to begin with it. Google's AI said it's between 80 million and 540 million (based on the brightness of a single satellite and the lowest brightness visible to the naked eye), but I'm hesitant to trust LLM generated math. Someone please help! [[User:Stroopwafel Falafel|Stroopwafel Falafel]] ([[User talk:Stroopwafel Falafel|talk]]) 18:16, 5 November 2025 (UTC)
:A single metre, at the distance from the Moon to GEO seems like it would subtend ~5.9x105 arcminutes of angle(near-side) to ~4.9x105 (far-side), give or take a little adjustment for exact viewpoint.
:Visual acuity is variously quoted as between a few arcseconds and about an arcminute, but that's more distinguishing one thing at one point in vision from another ''nearly'' at that point in it. Pinpricks of light distinguish themselves out from a background, of course. But it looks like that Venus is (optimally) from roughly 105,000 to 125,000 times as wide, or square those numbers for the ratio of solid angles, so we'd be talking about the level of far fainter stars.
:I think that (as specs of light, spread out) you don't ''necessarily'' need even a million of them, but it would be a tenuously-visible definable hairlike feature at best if you put m² 'blocks' edge-to-edge in an 'arc structure'. (Also, if you connected them, wouldn't the 'orbital Centre Of Gravity' be somewhere half way along the chord between the two ends, changing the orbital period it wants to drift round at, or does the non-Newtonian rotating frame of reference let it sit on the 'mid-block' of the arc? Before considering gravitational pull ''between'' the blocks, of course.)
:But it'd be a 'whisp'. Perhaps folding out to tennis-court size (or larger), plus relying on the perfect orientation for visible reflection from their surface would help. You could leave them drifting hundreds of metres apart, or further, each point notable more for being part of a linear 'asterism' of faint points (like a more compact Milky Way effect), getting away with fewer.
:So are we talking of enough satellites to be 'large enough and close enough' to make such a whisp (at near/far extremes) and then extrapolating to what this linear density means a fully-filled orbit would need? (Rather than bunches of them, suggesting the whole orbit only by a 'dashed line', each dash made up of dots.)
:Looking at it from the other side, the ''width'' of GEO, seen from the Moon, would be about 10-degrees of arc (very visible, assuming the points of the arc are). Theoretically 224 million "metre-cubes" elbow-to-elbow would fill it... in a (thinner-than-)hair-thin structure, but those tennis courts (or, lets get ambitious, football-field sized... ''any' kind of football, but perhaps Aussie Rules would be a useful aspiration), all at handy Sun-reflecting angles..? They could be less dense, far from touching. Be creative with geosynchronous-but-not-geostationary orbital constellations, and it'd thicken-up that hairline feature (at the expense of the satellites needed maybe being a simple multiple, to deal with off-equatorial dispersion of 'density').
:I'm most worried about the need to individually control each flat reflector to make best visible to a given Moon-observer, though. Feel free to recalculate for (say) silvered spherical 'inflatable' satellites, or something, of some size ''probably'' nowhere near that of a sporting arena. But we definitely need to know more about the albedo-/reflecti ity-profile of whatever we try to spatter around the orbit, before we can tie down everything else about the problem. [[Special:Contributions/82.132.246.185|82.132.246.185]] 19:49, 5 November 2025 (UTC)