explain xkcd - User contributions [en]

Talk:1717: Pyramid Honey

2016-08-08T16:06:14Z

173.245.54.51:

Seems like this could be the [http://www.smithsonianmag.com/science-nature/the-science-behind-honeys-eternal-shelf-life-1218690/ Smithsonian reference]! --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 13:53, 8 August 2016 (UTC)

Anyone know what the counter source or argument is?

This looks like it could be the source that inspired the strip:

http://irna.lautre.net/Honey-in-the-pyramids.html

Looks like a place to start digging for references: http://bumblehive.com/honey-was-not-found-in-pharaohs-tombs/ 

Did Randall draw the wrong colored hat?? [[User:Jameslucas|jameslucas]] ([[User talk:Jameslucas|" "]] / [[Special:Contributions/Jameslucas|+]]) 15:09, 8 August 2016 (UTC)
: Nah, I think it's just IRL trolling. [[Special:Contributions/173.245.54.80|173.245.54.80]] 15:34, 8 August 2016 (UTC)

Could this be the ned of Black Hat? The end of ''xkcd?!'' [[Special:Contributions/173.245.54.51|173.245.54.51]] 16:06, 8 August 2016 (UTC)

Talk:1713: 50 ccs

2016-07-29T16:19:55Z

173.245.54.51:

I don't fully get this joke but I do get that people do all sorts of strange things to cure hiccups so I think it has to do with that but I don't understand the title text at all [[User:MrEnder|MrEnder]] ([[User talk:MrEnder|talk]]) 05:26, 29 July 2016 (UTC)

Thinking more CCs is a measurement of medicine usually referring to pain killers. Maybe people are coming in with the hiccups and the doctor is going to hand out pain killers (or just sugar pills) saying they are a hiccup vaccine and is annoyed at having to do so. So this could be a joke about placebo drugs. [[User:MrEnder|MrEnder]] ([[User talk:MrEnder|talk]]) 05:33, 29 July 2016 (UTC)
:No, 1 cc here literally mean "cc" which is egnogh c's to spell va'''cc'''ination -- so 25 cc's is literally "cccccccccccccccccccccccccccccccccccccccccccccccccc" [[Special:Contributions/162.158.255.113|162.158.255.113]] 13:53, 29 July 2016 (UTC)

50cc is a volume measurement typically used to measure injectible dosages. A metric measure meaning "cubic centimetre" it is equivalent to 1 millilitre. Thus, the title is referring to volume of injection. However, the words hiccup and vaccine both include the letter combination "cc", hence writing them down 25 times each will be a total of 50 "cc" words. This is supported by the additional "cc" words in the mouseover text
[[Special:Contributions/141.101.98.78|141.101.98.78]] 05:36, 29 July 2016 (UTC)

Folks, it's a matter of spelling: it takes 50 pieces of the letters "cc" to write "hiccup vaccine" 25 times {{unsigned ip|162.158.85.141}}

Could it be related to http://xkcd.com/1383/ ? [[Special:Contributions/198.41.242.241|198.41.242.241]] 05:45, 29 July 2016 (UTC)
:No I see no connection. This is about words with cc and the volume cm^3 as cc, whereas the [[1383: Magic Words]] is about language and sex... --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 14:24, 29 July 2016 (UTC)

Just noticed something else! maybe coincidence! But raccoons are known to have rabies. If you read the title texts first letters of the description of what happened you get R A A A A B (could be pronounced Ray Bee) because accordions have nothing to do with women's roman drinking and ecstasy parties as far as I can tell [[User:MrEnder|MrEnder]] ([[User talk:MrEnder|talk]]) 05:47, 29 July 2016 (UTC)
:#overthinking [[Special:Contributions/141.101.104.115|141.101.104.115]] 11:10, 29 July 2016 (UTC)
::Agree ;-) --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 14:24, 29 July 2016 (UTC)

Y'all are making this too complicated. It's the classic garden-path joke which says something simple and obvious, then says something that completely changes the meaning of what went before. "I shot an elephant in my pajamas. I don't know how he got into my pajamas." [[Special:Contributions/108.162.237.136|108.162.237.136]] 14:17, 29 July 2016 (UTC)
:Is that not what the explanation says? --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 14:24, 29 July 2016 (UTC)

Drinking has been known to cause hiccups. Do you think the raccoons from the bacchanalia are the ones who need the hiccup vaccine? [[Special:Contributions/173.245.54.51|173.245.54.51]] 16:19, 29 July 2016 (UTC)

Talk:1133: Up Goer Five

2016-07-12T18:38:53Z

173.245.54.51:

Isn't this comic essentially just saying 'rocket science: not actually as complicated as the phrase "it's not rocket science" would have us beleive'{{unsigned|203.211.80.97}}

This comic is also a celebration of what many people, presumably including former NASA employee Randall, consider the greatest technological achievement ever. {{unsigned|158.169.131.14}}
:Nope, Randall thinks delivery pizza is the most important thing humanity ever achieved (http://www.explainxkcd.com/wiki/index.php/638:_The_Search). [[Special:Contributions/141.101.104.49|141.101.104.49]] 15:20, 7 May 2015 (UTC)

I'm surprised "ship" isn't among the most commonly used words in English. Where do these statistics come from? [[User:Davidy22|Davidy22]][[User talk:Davidy22|<tt>(talk)</tt>]] 12:35, 12 November 2012 (UTC)

:It makes sense that "capsule" and "spaceship" (as one word) are not in the "ten hundred" most-common words (Really, "thousand" isn't on this list either?), but not "fuel" and/or "tank"? People (context: US Midwesterner) talk about filling up their cats all the time! I'd like to see the original 1,000-word list. (Also: "Up Goer"? Well, it goes up -- that's about ALL it does. Makes sense, I guess.) --BigMal27 // [[Special:Contributions/192.136.15.149|192.136.15.149]] 13:13, 12 November 2012 (UTC)

Maybe is Randall referring to [[wikipedia:Simplified Technical English|Simplified Technical English]]? — [[User:Ethaniel|Ethaniel]] ([[User talk:Ethaniel|talk]]) 14:09, 12 November 2012 (UTC)
:There is an entry in the Simple English Wikipedia: http://simple.wikipedia.org/wiki/Simplified_English . The Simple English Wikipedia is interesting to browse, and challenging to write articles for. [[User:J-beda|J-beda]] ([[User talk:J-beda|talk]]) 14:24, 12 November 2012 (UTC)
:: Look up Basic English. It is the 850 most used words (or rather the 850 most used words when it was invented in 1930). According to Wikipedia it is still used in some countries as the basic vocabulary to first teach in English. The list of words is here: http://en.wiktionary.org/wiki/Appendix:Basic_English_word_list . It looks like this could be what he used.i[[User:Carewolf|Carewolf]] ([[User talk:Carewolf|talk]]) 17:30, 14 November 2012 (UTC)
::: The 850 Basic English word list includes "liquid" and "second" but does not include "world", "five" and "third" so we're still looking for the vocabulary list.
I'm inclined to think this is also a nod to 1984's {{w|Newspeak}}, and the dumbing-down effect of an ''overly'' {{w|controlled language}}. It's good to simplify (linguistic) complexity, but with that simplification of text comes a simplification of capacity, too. We push back horizons by exploring unknowns, so restricting things to a small set of knowns may be counterproductive. -- [[User:IronyChef|IronyChef]] ([[User talk:IronyChef|talk]]) 15:13, 12 November 2012 (UTC)
:This is the very point I am trying to make time and again. Some topics cannot be correctly explained to everyone. BTW XKCD #547 had a similar point.

::I think that's a very unfortunate "point" to be trying to make time and time again. My personal feelings aside, it goes against Randall's and xkcd's ethos, as well. Just as in law or any other specialized area, an expert, given a reasonable amount of time, thought, and vocabulary, should be able to explain even very complex ideas to lay persons. If there's a failure to do so, the burden should rest with the explainer. And frankly, that failure might even expose some lack of understanding on the explainer's end, as well. I have discussed this in greater depth below. [[User:Orazor|Orazor]] ([[User talk:Orazor|talk]]) 09:10, 19 September 2014 (UTC)

The comic is almost certainly using http://en.wiktionary.org/wiki/Appendix:Basic_English_word_list or another work list like it.[[Special:Contributions/82.16.27.115|82.16.27.115]] 16:58, 12 November 2012 (UTC)

The phrase in the explanation "Helium is much less prone to catching fire" brought a smile to my lips as there is literally <SIC> nothing less prone to catching fire than Helium. [[Special:Contributions/90.208.12.4|90.208.12.4]] 23:10, 12 November 2012 (UTC)

:<s>Unfortunately some pedant has changed it to the technically correct, but much less smile-inducing "inflammable". Pitty, it made me smile too.</s> [[User:Lcarsos|lcarsos]] ([[User talk:Lcarsos|talk]]) 23:22, 12 November 2012 (UTC)

:Edit: I've reverted it, because the whole edit was fraught with incorrect minor changes. 23:27, 12 November 2012 (UTC)

:Inflammable is '''wrong'''. It means the same as flammable. If you mean 'incapable of burning', the opposite of flammable/inflammable is ''nonflammable''. This is one of the subtleties of English which is avoided by using a greater number of simple words! [[Special:Contributions/87.252.61.205|87.252.61.205]] 13:01, 13 November 2012 (UTC)

::I wouldn't say Helium is least prone to catching fire. Sure, it's least prone to chemical reaction, but it is prone to nuclear fusion, which looks sort of like fire. On the other hand Iron, while it can be oxygenated, doesn't really catch fire doing that and I doubt it can chemically react in a way which would look that way. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 08:42, 14 November 2012 (UTC)

:::Fire is strictly defined as the rapid oxidation of a substance in the presence of heat - nuclear fusion is transmutation, not combustion. Iron can undergo a thermite reaction which makes spectacular flying flames. Youtube should have a billion videos of thermite reactions for your perusal. [[User:Davidy22|Davidy22]][[User talk:Davidy22|<tt>(talk)</tt>]]

:::Fine steel wool (such as 0000 grade) burns exceedingly well. A survival technique is to use flashlight batteries to make a spark in the steel wool, which then becomes an excellent fire starter.

Since the comic can't use the actual words, it took me some time to find Wikipedia's articles that describe the actual "up goer." In case there's anybody like me who wanted to know more details, I found the {{w|Apollo (spacecraft)}} and {{w|Saturn V}} articles to be very interesting and relevant. BTW, "that stuff they burned in lights before houses had power" is {{w|RP-1|highly refined kerosene}}. [[User:S|S]] ([[User talk:S|talk]]) 00:34, 13 November 2012 (UTC)

:Thanks for doing the research! I've incorporated this into the explanation. Feel free to add more if you think it needs more. [[User:Lcarsos|lcarsos]] ([[User talk:Lcarsos|talk]]) 01:33, 13 November 2012 (UTC)

::I like your additions. Much better than what I could come up with! [[User:S|S]] ([[User talk:S|talk]]) 23:44, 14 November 2012 (UTC)

It would be pretty nice for a day if everyone just spoke using the most used thousand words in his respective language. Just off hand, describing the band name "Led Zeppelin" would certainly be a treat--[[User:Dangerkeith3000|Dangerkeith3000]] ([[User talk:Dangerkeith3000|talk]]) 18:10, 13 November 2012 (UTC)

:Anyone who will not be fired off trying to only speak the most used thousand words for workday is working manually or not at all. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 08:42, 14 November 2012 (UTC)

::Or is a school teacher, or working primarily with people who have language difficulties...

I think NASA should rebrand themselves "US Spaaaaaace Team" it's so much cooler than the "National Aeronautics and Spaaaaaace Administration"! --[[User:NHSavage|NHSavage]] ([[User talk:NHSavage|talk]]) 07:39, 15 November 2012 (UTC)

I have not once heard the word "goer" before this. Thousand most common? [[Special:Contributions/67.52.144.154|67.52.144.154]] 16:22, 15 November 2012 (UTC)

:Randall used the verb "to go" and as it's a verb, any conjugation could be considered the same word. I think that's where he got "goer" from. [[User:Lcarsos|lcarsos]]_a ([[User talk:Lcarsos|talk]]) 16:29, 15 November 2012 (UTC)
::Well, not a conjugation, a different part of speech. That's a slightly more extreme leap than a change of inflection, but probably still allowable for these purposes. [[User:Jerodast|- jerodast]] ([[User talk:Jerodast|talk]]) 15:18, 3 December 2012 (UTC)

Someone has made an "Up-Goer Five Text Editor", with a link to a (the?) ten-hundred wordlist: http://splasho.com/upgoer5/. [[Special:Contributions/83.233.5.126|83.233.5.126]] 18:46, 21 January 2013 (UTC)

I'm having trouble believing that lift off is not on the common word list. [[User:DruidDriver|DruidDriver]] ([[User talk:DruidDriver|talk]]) 01:55, 23 January 2013 (UTC)

'''On language and explaining'''

Strongly disagree with the contention at the beginning of this explanation that "This comic is a commentary on the absurdity of boiling down technical explanations for lay people..." On many occasions Randall de-jargonizes/simplifies complex ideas so that they can be understood by most anyone. Heck, he dedicates an entire blog (whatif) to it. In this interview with fivethirtyeight.com, (http://fivethirtyeight.com/datalab/xkcd-randall-munroe-qanda-what-if/) among others, Randall explains that lay persons, given enough time, patience, and the correct guidance, should be able to understand most any scientific/technical idea.

To wit: "It’s tempting to think of technical audiences and general audiences as completely different, but I think that no matter who you’re talking to, the principles of explaining things clearly are the same. The only real difference is which things you can assume they already know[.] ... I’m always looking for ways of looking at problems — mental models — that make the answers intuitively clear. Once I’ve hit on one of those, '''I just try to explain it as simply and clearly as I can[.]'''"

Accordingly, I have altered the explanation to reflect this world view. The point of this comic is to illustrate that one should be able to explain complicated ideas to people who lack a technical background using simple language. Granted that Randall is imposing upon himself an unreasonable "ten hundred word" linguistic restriction, but I think that only goes to further his point. Unless the "explainee" is being unreasonably obtuse, the burden falls upon the shoulders of the explainer to help a non-lay audience understand. [[User:Orazor|Orazor]] ([[User talk:Orazor|talk]]) 08:53, 19 September 2014 (UTC)

If you don't go to spaaaaaace today, you need more struts[[User:Steammaster|Steammaster]] ([[User talk:Steammaster|talk]]) 18:43, 19 January 2015 (UTC)

:or more boosters! (Both are popular ''Kerbal Space Program'' catchphrases.) [[Special:Contributions/108.162.230.179|108.162.230.179]] 10:50, 3 June 2015 (UTC)

Maybe we should add a reference to Randall's upcoming book, Thing Explainer. [[Special:Contributions/108.162.216.109|108.162.216.109]] 02:14, 28 May 2015 (UTC)

As I understand it, the brackets in "oh the [humans]" are used to indicate paraphrasing (replacing "humanity" with "humans") as is common in English texts. Referring to humanity with the phrase "concentration of humans" seems rather contrived and unlikely. Any opinions on this?
--[[Special:Contributions/173.245.54.51|173.245.54.51]] 18:38, 12 July 2016 (UTC)

1704: Gnome Ann

2016-07-10T02:17:38Z

173.245.54.51: /* Explanation */

{{comic
| number = 1704
| date = July 8, 2016
| title = Gnome Ann
| image = gnome_ann.png
| titletext = In the words of Andrew Johnson, if I am to be shot at, I want Gnome Ann to be in the way of the bullet.
}}

==Explanation==
This comic presents a series of images depicting a female {{w|gnome}} who is known as "Gnome Ann". The humor derives from the fact that the name "Gnome Ann" and the compound noun "no man" are {{w|homophone}}s, meaning they sound alike but have different meanings and spellings.
(Users of the {{w|GNOME|Gnome desktop system}} may have difficulties understanding this since they pronounce Gnome with a hard "g", reflecting its {{w|GNU}} ties.)

[[Randall]] presents the reader with six images (and a title text) captioned with quotations from a wide range of sources, each featuring an instance of the compound noun "no man" being replaced by "Gnome Ann" (and featuring a drawing that reflects this change). There is one proverb, two Biblical quotations, two literary quotations (the {{w|Miguel de Cervantes|Cervantes}} quote is from ''{{w|Don Quixote}}'', the other one is from {{w|Lord of the Rings}}, the line {{w|Éowyn}} said to the {{w|Witch-king_of_Angmar|Witch-king of Angmar}} before killing him), one quotation from the opening of a television show (''{{w|Star Trek: The Original Series}}''), and a quotation from a piece of historical rhetoric in the title text.

The third panel, in which Gnome Ann pushes the groom aside and approaches the bride, may suggest that Gnome Ann is attracted to her and perhaps intends to marry her in his stead. According to {{w|Joseph Smith}}, Gnome Ann shall have but one wife. [https://en.wikipedia.org/wiki/Origin_of_Latter_Day_Saint_polygamy] (And, incidentally, [https://en.wikisource.org/wiki/King_Follett_Discourse#A_Call_to_Repentance knows his history].)

The process by which "no man" becomes "nom an" (and hence Gnome Ann) is known as {{w|false splitting}}, and is a familiar process of word formation in English and other languages; examples include {{w|Vipera_berus#Etymologies|"an adder" from "a nadder"}} and "lone" from "(all) one".

===Table of quotes===
{| class="wikitable"
| '''Modified quote'''
| '''Original quote'''
| '''Origin'''
| '''Explanation'''
|-
| "Time and tide wait for Gnome Ann."
| "Time and tide wait for no man."
| Proverb
| [[89: Gravitational Mass|Normally]] it is not possible for anyone to influence time or tides. However in this case it would appear that Gnome Ann is able to stop time, and tides.
|-
| "The wicked flee when Gnome Ann pursueth."
| "The wicked flee when no man pursueth."
| Bible: [http://biblehub.com/proverbs/28-1.htm Proverbs 28:1]
| This (out of context) biblical reference normally implies the wicked are a cowardly and/or paranoid lot, jumping at shadows and eager to flee at simply the pretense of danger or pursuit. However in this case it would imply that wicked people run away from Gnome Ann specifically.
|-
| "What therefore God hath joined together, let Gnome Ann put asunder."
| "What therefore God hath joined together, let no man put asunder."
| Bible: [http://biblehub.com/mark/10-9.htm Mark 10:9]
| In the Bible, Jesus is asked about whether people should be allowed to divorce, and Jesus responds with this quote. It is known to appear in wedding vows, hence the fact that the man and woman in the panel are dressed for a wedding. However, in the comic, the quote becomes a command to Gnome Ann to break apart what God has joined.
|-
| "Time ripens all things; Gnome Ann is born wise
| "Time ripens all things; no man is born wise."
| The novel {{w|Don Quixote}} by {{w|Miguel De Cervantes}}
| This states that nobody is wise to begin with, and it takes time to become wise. However it now states that Gnome Ann is wise to begin with, suggesting she is not part of the order of things within time.
|-
| "Our Mission: To boldly go where Gnome Ann has gone before."
| "Our Mission: To boldly go where no man has gone before."
| Intro at {{w|Star Trek: The Original Series}}
| Originally this was meant to emphasize that they would be going to completely unexplored territory, which would be a potentially risky venture. However in this case , it means that they will be following Gnome Ann, which is not exploration. Though depending on where Gnome Ann has gone, these may still be risky ventures: "(Gnome Ann) goes to battle to be killed." [https://en.wikipedia.org/wiki/Caesar_and_Cleopatra_%28play%29]
|-
| Witch-king of Angmar: "Fool! No man can kill me." Gnome Ann: "I Am Gnome Ann!"
| Witch-king of Angmar: "Fool! No man can kill me." Éowyn: "I Am no man!"
| {{w|The Lord of the Rings}}
| The Witch-king of Angmar was given a prophecy that he would never be bested in combat by the hand of man, and he boasted "no man" could kill him. Both in ''Lord of the Rings'' and this comic, he is defeated by a woman. Gnome Ann is simply that good. Note that in the Tolkien legendarium, a "Gnome" is an archaic name for the Noldor tribe of elves (e.g. Galadriel).
|-
| "In the words of Andrew Johnson, if I am to be shot at, I want Gnome Ann to be in the way of the bullet."
| "In the words of Andrew Johnson, if I am to be shot at, I want no man to be in the way of the bullet."
| {{w|Andrew Johnson}}, 17th President of the United States
| '''Title text''': The intent of this statement originally was that Andrew Johnson would rather be killed, than have somebody else be killed trying to save his life. However in this case it would appear that Andrew Johnson would really prefer Gnome Ann to be shot instead of himself, perhaps because he knows that "(Gnome Ann) lives forever." [https://en.wikiquote.org/wiki/Algernon_Charles_Swinburne]
|}

==Transcript==
:[Caption above the panels.]
:The <big>Legend</big> of <big>Gnome Ann</big>

:[At the beach, between a clock hanging in the air, showing 10 past 10 and the shoreline, Gnome Ann, a woman with curly hair and a black triangular hat, stands with her arms outstretched towards the clock and the sea. For each of the first five panels a text is written within a frame above the drawings.]
:Time and tide wait for Gnome Ann.

:[Gnome Ann running in from the left frame with her arms out chases three Cueball like men running from her towards right. The one closest to her looks over his shoulder at her, the next runs forward "normally" and the last in front throws up his arms in the air.]
:The wicked flee when Gnome Ann pursueth.
:-Proverbs 28:1

:[Gnome Ann takes the groom's place in a wedding, shoving him to the side. The groom, Hairy with a bow tie, falls while throwing his arms out. The bride stands to the left, in full wedding dress, showing no reaction.]
:What therefore God hath joined together, let Gnome Ann put asunder.
:-Mark 10:9

:[Gnome Ann sits in a yoga position meditating on a big rock in a desolate area with small rocks on the ground around the big rock.]
:Time ripens all things; Gnome Ann is born wise.
:-Miguel De Cervantes

:[The starship Enterprise from Star Trek is seen from behind as it flies to the right, chasing a smaller craft. In this panel the frame with text is shown to emanate from Enterprise with a zig zag arrow pointing to the starship.]
:Enterprise: Our Mission: To boldly go where Gnome Ann has gone before.

:[The Witch-king of Angmar, Lord of the Nazgûl, from the Lord of the Rings sits on his knees (below the frame) to the left of Gnome Ann, who is preparing to stab him with a sword pointing at his head. She is also holding her other arm out towards him. The Witch-king has a black cloak covering his head and body with a kind of crown with six small spikes shown around his head and one large spike in front. It also goes down on each side of his head showing a gaping hole instead of a face. In this panel the text is spoken by the two characters.]
:Witch-king: Fool! No man can kill me.
:Gnome Ann: '''''I Am Gnome Ann!'''''

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Hairy]]
[[Category:Multiple Cueballs]]
[[Category:Time]]
[[Category:Religion]]
[[Category:Fiction]]
[[Category:Star Trek]]
[[Category:LOTR]]
[[Category:Philosophy]]
[[Category:Comics featuring politicians]]

Talk:1555: Exoplanet Names 2

2016-05-31T16:56:16Z

173.245.54.51:

[https://www.youtube.com/watch?v=znxFrgql5dc "This Land"] is a ''Firefly'' reference. [[User:Keavon|Keavon]] ([[User talk:Keavon|talk]]) 05:11, 24 July 2015 (UTC)
: This land is also track n6 of The Lion King, I think Randall is also a fan of this.--[[User:NeoRaist|NeoRaist]] ([[User talk:NeoRaist|talk]]) 14:54, 24 July 2015 (UTC)

What is with Kepler-283? [[Special:Contributions/108.162.214.137|108.162.214.137]] 05:09, 24 July 2015 (UTC)
:283b is the phonetic spelling for Uranus (your-a-nus) and 283c is the phonetic spelling for Uranus (your-ay-nus) [[Special:Contributions/141.101.104.77|141.101.104.77]] 05:33, 24 July 2015 (UTC)

;Netherlands
.. I almost feel like that titletext gives enough reason for there to be (some) pages about the [[what_if?|''What If?'']] series, but ehhhh... [[User:Pixali|Pixali]] ([[User talk:Pixali|talk]]|[[Special:Contributions/Pixali|contribs]]) 05:02, 24 July 2015 (UTC)

Thought about that and Randall's "promise" to use this joke more often: Do we need a "Netherlands" category for comics/articles? Having said that, maybe this was the very last reference to this joke, because of this promise... [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 12:06, 3 August 2015 (UTC)

;Kostner
Is there a pun I'm missing by spelling Kevin Costner as "Kostner"? [[Special:Contributions/198.41.241.7|198.41.241.7]]
:[http://imgs.xkcd.com/comics/exoplanet_names_2.png Randall fixed it.] I don't know how to update the file here, though. [[User:P1h3r1e3d13|P1h3r1e3d13]] ([[User talk:P1h3r1e3d13|talk]]) 20:15, 24 July 2015 (UTC)
::I got it - the file's been updated, but I had to go all the way to the image and force a refresh on my browser for it to appear correctly. :P [[User:KieferSkunk|KieferSkunk]] ([[User talk:KieferSkunk|talk]]) 00:34, 25 July 2015 (UTC)

;Novella

I'm not 100% sure what "Novella" refers to, aside from the dictionary definition of the word (and if that's the case I'm unsure of the context), but in case it's not widely-known on this wiki, I want to suggest the possibility that it's a tribute to the Novella brothers, who are among the co-hosts of the popular science podcast The Skeptic's Guide to the Universe. - [[Special:Contributions/108.162.241.175|108.162.241.175]] 04:43, 24 July 2015 (UTC)

:Seems like a cool podcast, sadly I don't have time to listen to 10 years Witt of podcasts. Any specific ones I should listen to and where should I start for new ones? {{unsigned ip|173.245.55.63}}
:: The podcast is very topical, often talking about current news items. It is OK to start with new ones, and back-fill as desired. [[User:Blaisepascal|Blaisepascal]] ([[User talk:Blaisepascal|talk]]) 18:57, 24 July 2015 (UTC)
: Considering the sex-themed names Novella it is grouped with. I will assume it is a joke on 60/70's exploitation/B-movies, some of which had names or leadcharacters named something..-ella. In this case the prefix is just particularly confusing ;) [[Special:Contributions/188.114.110.47|188.114.110.47]] 08:51, 24 July 2015 (UTC)
::I assumed this was a reference to the SGU, perhaps because I was primed by the Phil Plait reference (who has been a guest on that podcast a few times), and because of their enthusiasm for space news. [[Special:Contributions/141.101.99.57|141.101.99.57]] 20:04, 28 July 2015 (UTC)
: It could also be interpreted in this context as the diminutive form of "nova," like a stellar nova. - [[Special:Contributions/173.245.56.165|173.245.56.165]] 15:09, 31 July 2015 (UTC)

;A$aplanet

Is a pun on the rap group {{w|A$AP Mob}} and their most prominient member {{w|A$AP Rocky}}.
: Included that possibility. Thanks. Didn't know of A$AP, before. [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 13:21, 24 July 2015 (UTC)

Somehow I just read this as "a dollar a planet", maybe refering to a donating scheme ("a dollar donated for every planet found" or even more along the lines of "a dollar a day", meaning: donate 1 dollar to save this planet) or a sale advertisement ("just $1 to buy a planet", which is very likely to be a scam as it would not be possible with current technology to visit another planet outside of our solar system) [[Special:Contributions/198.41.242.253|198.41.242.253]] 15:15, 24 July 2015 (UTC)

;Planet of the Apes (disambiguation)
I think the suggestion here is to actually put the "(disambiguation)" in the name of the planet, thereby creating a problem in the wikipedia entry, since [https://en.wikipedia.org/wiki/Planet_of_the_Apes_%28disambiguation%29 there's already a wikipedia page with that title]. They would have to create a meta-disambiguation page, which is why this is funny. [[Special:Contributions/141.101.98.235|141.101.98.235]] 13:39, 24 July 2015 (UTC)

::That's definitely the joke. But Wikipedia is actually already prepared to deal with this. When the Prince and the Revolution cover band "Prince (disambiguation)" tried to add a page for their band, editors pointed out that it should be listed as "Prince (disambiguation) (band)", with that "misnamed for technical reasons" template at the top explaining that the band's proper name is "Prince (disambiguation)", and possibly a disambiguation page at "Prince (disambiguation)" could point to it as well as to "Prince (musician)" and various other things. (But of course the band is completely non-notable, so the page was just deleted anyway). (I may be misremembering the details; it may have been a similarly-named cover band for a similar artist.) So, this would just be "Planet of the Apsa (disambiguation) (exoplanet)". [[Special:Contributions/162.158.255.52|162.158.255.52]] 17:17, 28 September 2015 (UTC)

;Kepler-438b
In the previous comic, Kepler-438 was named Kepler-1686 (which does not seem to exist...) and was updated to the current [http://en.wikipedia.org/wiki/Kepler-438b Kepler-438b]. It even is colored red to show the update. [[Special:Contributions/162.158.23.198|162.158.23.198]] 16:34, 24 July 2015 (UTC)

;Hot Mess

Why is Hot Mess an Arrested Development thing? The phrase is in general use, not just limited to viewers of that show. {{unsigned ip|108.162.237.189}}

;Air Bud Pluto #9 Reference
A few strips back, in ''Rulebook'', we were debating whether the "9" on the dog's jersey may have been a subtle jab at the Pluto debate. I argued that there was a strong possibility of that, given the timing of that comic immediately after the New Horizons flyby, the strong relationship between dogs and the name Pluto, and Pluto's former status as the 9th planet. There was no way to prove that that was what Randall had in mind (short of him personally confirming it), but I think this strip could lend some credence to it. What do you think? [[User:KieferSkunk|KieferSkunk]] ([[User talk:KieferSkunk|talk]]) 17:50, 24 July 2015 (UTC)

:What I think: #1 I don't think just the mention of Pluto is enough to support the relationship between Air Bud and Pluto; #2 read my commentary on [[1552: Rulebook]]. [[User:GuiRitter|GuiRitter]] ([[User talk:GuiRitter|talk]]) 23:01, 19 January 2016 (UTC)

;Definition of Planet
What about the fact that the new definition of planet made by the IAU says it has to be around the sun. None of these would fit the definition of planet then and the answer to "is Pluto a planet" would still be no.[[User:Agent0013|Agent0013]]
: Here's a link to the IAU resolution which defines a planet (and confirms Agent0013's comment): [http://www.iau.org/news/pressreleases/detail/iau0603/ IAU 2006 General Assembly Results]. [[Special:Contributions/173.245.50.150|173.245.50.150]] 19:35, 25 July 2015 (UTC)
::<Here used to be nonsense, sorry> [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 12:51, 3 August 2015 (UTC)

;Planet with Arms
(I just added this to the 1253 talk. Adding it here too.) I think Planet With Arms refers to both Hitchhiker's and to Galileo describing Saturn as a 'planet with ears' when he discovered. it. --[[Special:Contributions/173.245.54.26|173.245.54.26]] 13:12, 25 July 2015 (UTC)

A few more possibilities for you:
*"Skydot" - a reference to Carl Sagan's famous "Pale Blue Dot" of Earth.
*"Seas of Toothpaste" - possibly referencing the Beatles' "Yellow Submarine" with its various peculiar "Seas" (e.g., "Sea of Phrenology", "Sea of Holes")
*"Moonchild" is a generic hippy name, and also the title of a 1917 novel by Aleister Crowley and songs by King Crimson and Iron Maiden. The King Crimson song, perhaps importantly, is the fourth song (i.e., "song d") on their debut album.
* "Planet With Arms" also follows on directly after "LEGoland" as a pun, as well as referencing Galileo's description of Saturn as a planet with ears.
[[User:Grutness|Grutness]] ([[User talk:Grutness|talk]]) 01:48, 26 July 2015 (UTC)

Planet with arms could also probably be a reference to the 'birds with arms' meme. [[Special:Contributions/108.162.249.169|108.162.249.169]] 09:12, 26 July 2015 (UTC)

It's probably not intentional, but '''Spherical Discworld''' reminded me of an aspect of the Pratchett novel, ''Strata'' (pre-Discworld-series, i.e. ''very'' early work, and arguably a bit rough around the edges, but you still might want to peruse it some time). Although I'm not wanting to go into any more detail lest I spoiler the very interesting thing that I'm talking about. [[Special:Contributions/141.101.98.168|141.101.98.168]] 21:18, 26 July 2015 (UTC)

I am vaguely disappointed that none of the Eridani planets got named "Planet of the Fish Assholes"... -Pennpenn [[Special:Contributions/108.162.250.162|108.162.250.162]] 23:46, 26 July 2015 (UTC)

Can we talk about how this comic is the fourth time the island {{w|Sulawesi}} was mentioned without any reason? Sulawesi appeared in [[273: Electromagnetic Spectrum|comic 273]] as part of the electromagnetic spectrum, and physically in both Online Communities maps [[256: Online Communities|I]] and [[802: Online Communities 2|II]]? [[Special:Contributions/108.162.225.133|108.162.225.133]] 09:55, 27 July 2015 (UTC)

:I vote for a Sulawesi category. [[User:GuiRitter|GuiRitter]] ([[User talk:GuiRitter|talk]]) 23:01, 19 January 2016 (UTC)

Was unicodesnowmanforyou.com made before or after this comic came out?

681: Gravity Wells

2016-01-27T14:32:29Z

173.245.54.51: /* Explanation */ Moved reference to Randall's error to another spot since it has been corrected.

{{comic
| number = 681
| date = December 28, 2009
| title = Gravity Wells
| image = gravity_wells.png
| titletext = This doesn't take into account the energy imparted by orbital motion (or gravity assists or the Oberth effect), all of which can make it easier to reach outer planets.
}}
{{TOC}}

The xkcd page links to [http://xkcd.com/681_large/ a much larger version].

==Explanation==

The comic shows the gravitational potential (energy transferred per unit mass due to gravity) for the positions of each planet in the solar system -- including some moons and Saturn's rings. An object traveling along an upward slope loses energy, while an object traveling along a downward slope gains energy.

Escaping a planet or moon's orbit requires enough energy (e.g. by walking, jumping, or rocket) to reach the top of either peak that defines the edge of the well. The peak to the left indicates the minimum energy required to exit orbit. The peak to the right indicates the maximum energy required to exit orbit. In order to exit orbit with the minimum amount of energy, you would have to travel towards the center of the solar system; to exit orbit with the maximum amount of energy, you would have to travel away from the center of the solar system (the Sun). In reality, the strength of gravity decreases with distance from the planet. However, a comparison of energy expended to escape the gravitational pull allows for a simpler comparison between the objects.

The height of the graph is scaled to kilometers via the gravitational potential an object has at the given height assuming at a constant acceleration due to Earth's surface gravity. The {{w|Sun|Sun's}} gravity well is not shown in its entirety, but is just indicated on the far left as ''"Very very far down"''. Had it been shown in its full extent it would have made the rest of the drawing so small in comparison that it would have been unreadable. As the gravitational potential increases with distance from the sun the graph has a general upward slope. To rise out of each well on the diagram, and therefore escape the planets gravity, it would require the same energy required to rise out of a physical well of that depth at Earth's surface gravity.

The length of each gravity well is scaled to the diameter of the planet and the spacing between the planets is not to scale with distance from the sun. This is necessary to make the graph readable. Because the distance between the planets are condensed the gravitational potential, from the gravity pulling toward the sun, accumulates quicker. This is the reason for the large peaks between the planets. The moons shown in the chart are at the appropriate distance from their respective planets' gravity wells for their orbits.

Each planet is shown cut in half at the bottom of its well, with the depth of the well measured down to the planet's flat surface.

==== Inner Planets ====
* {{w|Mercury_(planet)|Mercury}} -- no facts listed
* {{w|Venus_(planet)|Venus}} -- no facts listedc
* {{w|Earth}} and {{w|Moon}}: The listed depth of the gravity well at Earth was originally listed at 5478 km rather than the correct value of 6379 km seen in the cutout. Randall has since corrected it. The Moon's is 288 km.
* {{w|Mars}}: The listed depth of the gravity well of Mars is 1286 km.

==== Outer Planets ====
* {{w|Jupiter}}: Jupiter is so massive and dense that it is comparable in mass to a {{w|Brown dwarf}} which is the smallest kind of star. Saturn, while similar in size, is composed of much lighter gas material. Hence Saturn's mass and therefore its gravitational pull are much smaller. Had a few dozen times the mass of gasses contained in Jupiter condensed in that location, the gravitational pull would cause the pressure and temperature to increase to a level that is sufficient to ignite {{w|Nuclear fusion|nuclear fusion}}. Had that happen during creation of our solar system, we would have two {{w|Sun|Suns}} and our solar system would be a {{w|Binary system (astronomy)|Binary system}}. Jupiter has {{w|Moons_of_Jupiter|67 moons}} of which 3 are shown;
** {{w|Ganymede_(moon)|Ganymede}} -- moon of Jupiter, no facts given
** {{w|Io_(moon)|Io}} -- moon of Jupiter, no facts given
** {{w|Europa_(moon)|Europa}} -- moon of Jupiter, no facts given

* {{w|Saturn}}: The diagram shows the position of the {{w|rings of Saturn}} in Saturn's gravity well. Saturn's rings start fairly near the planet and extend out quite far, therefore multiple stripes are shown in the figure. The rings are also shown in multiple colors and roughly match the observed colors from photos take by the {{w|Cassini–Huygens|Cassini spacecraft}} expedition as it passed Saturn. All of the colors of the planets and moons represent the predominant color of that object as observed from earth. Saturn has {{w|Moons_of_Saturn|62 moons}} of which one is shown;
** {{w|Titan (moon)|Titan}}, a moon of Saturn. The figures on Titan are sirens, a reference to Kurt Vonnegut's ''{{w|The Sirens of Titan}}''.

* {{w|Uranus}}: Notably absent is any "your-anus" jokes.
* {{w|Neptune}}: Megan's quote is a paraphrase of {{w|Carl Sagan|Carl Sagan's}} quote, "...but from a planet orbiting a star in a distant globular cluster, a still more glorious dawn awaits, not a sun-rise, but a galaxy rise." [http://www.youtube.com/watch?v=zSgiXGELjbc Video here]

==== Cut outs and sketches====
The following items are listed from top to bottom and left to right.

* Mars moons: The Mars cutout shows the Mars moon system, including the moons Deimos and Phobos. The depth of the Mars gravity well is listed at 1286 km.
** {{w|Deimos (moon)|Deimos}}: The gravity on Deimos, a moon of Mars, is so weak that a bike jump would be sufficient to escape its gravity.
** {{w|Phobos (moon)|Phobos}}: The gravity on Phobos, a moon of Mars, is so weak that you could launch a baseball into space simply by throwing it.

* Your mom and a local football team: The sketch next to Jupiter is playing on the classic "Yo Mama" joke. It combines "Yo Mama is so fat" and "Yo Mama is so horny". The sketch implies that she has a huge gravitational pull because she is very fat, and has sex with an entire football team by demonstrating a football team falling into her very deep gravity well. A "Yo Mama" joke also appears in comic [[89: Gravitational Mass]].

* Earth's Moon: The cut out shows the significant difference in strength between the {{w|gravity well}} of the Earth and the Moon. Cueball comments that the {{w|Apollo Lunar Module|Apollo Lunar Module}} was very small and the {{w|Saturn V}} rocket was very large because escaping the Earth's gravity well takes much more energy than escaping the Moon's. The cut out also shows that objects like the {{w|International_Space_Station|International Space Station}}, the {{w|Space shuttle|space shuttle}}, {{w|GPS satellite|GPS satellites}} and {{w|Geostationary orbit|geo-stationary satellites}} at their respective positions within Earth's gravity well. The depth of Earth's gravity well is listed correctly at 6 379 km (note the difference from the non-cutout number). The depth of the Moon's gravity well is listed at 288 km.

=== How to calculate gravity wells ===
The text near the bottom of Jupiter's gravity well explains that the depth of the well is mass-of-planet over radius-of-planet with Newton's constant and 9.81 m/s² as constants, where 9.81 m/s² is the acceleration of a free falling body at Earth's gravity.

The calculation for a gravity well is:
:depth = (G * Planet-mass ) / (9.81 m/s2 * Planet-radius)
::where G is {{w|Isaac_Newton|Newton}}'s {{w|Gravitational_constant|gravitational constant}}, and
::9.81 m/s2 is the {{w|Acceleration|acceleration}} rate of a {{w|Gravity_of_Earth|free falling body on earth}} at sea level (g).

====Title text====
The title text indicates that the planets motion can affect the amount of energy for escape velocity. It is possible to change speed by using the planets orbital speed and gravity. This is know as a performing a slingshot or a {{w|Gravity assist|gravity assist}}, and is done to gain speed or to brake when needed. The use of rocket engines are more effective when used at a high speed slingshot maneuver, which is know as the {{w|Oberth effect}}, where most energy is going into moving the rocket as opposed to moving the exhaust -- conserving the maximum useful energy. On earth the same principle is used when launching rockets. Rockets are always launched in a eastward direction to make maximum use of the rotational energy of the earth. Launching rockets in a westward direction would require significant additional energy. Because of this most artificial satellites are flying east around the globe.

The size of the gravity-well as described in this comic is not accounting for these factors. Therefore leaving the solar system (or any of the gravity wells of the planets) could require less energy than described by the graph, assuming that the launch and slingshots are properly designed and executed.

==== Escape Velocities ====
The following table was adapted from the table in {{w|Escape velocity#List of escape velocities|Escape velocity}}, using ''h'' = ''V_e''^2 / 2''g'':
{| class="wikitable" border="1"
| Location || with respect to || Ve (km/s) || Well depth (km) ||
| Location || with respect to || Ve (km/s) || Solar well (Mm) || Total depth (Mm)
|-
| on the Sun, || the Sun's gravity: || 617.5 || 19,435,000 || || || || || || 19,435
|-
| on Mercury, || Mercury's gravity: || 4.3 || 942 ||
| at Mercury, || the Sun's gravity: || 67.7 || 233.6 || 235
|-
| on Venus, || Venus' gravity: || 10.3 || 5,407 ||
| at Venus, || the Sun's gravity: || 49.5 || 124.9 || 130
|-
| on Earth, || the Earth's gravity: || 11.2 || 6,393 ||
| at the Earth/Moon, || the Sun's gravity: || 42.1 || 90.3 || 97
|-
| on the Moon, || the Moon's gravity: || 2.4 || 294 ||
| at the Moon, || the Earth's gravity: || 1.4 || || 91
|-
| on Mars, || Mars' gravity: || 5 || 1,274 ||
| at Mars, || the Sun's gravity: || 34.1 || 59.3 || 61
|-
| on Jupiter, || Jupiter's gravity: || 59.5 || 180,400 ||
| at Jupiter, || the Sun's gravity: || 18.5 || 17.4 || 198
|-
| on Ganymede, || Ganymede's gravity: || 2.7 || 372 || || || || ||
|-
| on Saturn, || Saturn's gravity: || 35.6 || 64,600 ||
| at Saturn, || the Sun's gravity: || 13.6 || 9.43 || 74
|-
| on Uranus, || Uranus' gravity: || 21.2 || 22,907 ||
| at Uranus, || the Sun's gravity: || 9.6 || 4.7 || 28
|-
| on Neptune, || Neptune's gravity: || 23.6 || 28,400 ||
| at Neptune, || the Sun's gravity: || 7.7 || 3.02 || 31
|-
| on Pluto, || Pluto's gravity: || 1.2 || 73 || || || || ||
|-
|at Solar System galactic radius, || the Milky Way's gravity: || 525 || 14,000
|}

==Transcript==
:'''Main Text'''
:Gravity Wells scaled to Earth surface gravity
:This chart shows the "depth" of various solar system gravity wells.
:Each well is scaled such that rising out of a physical well of that depth — in constant Earth surface gravity — would take the same energy as escaping from that planet's gravity in reality.
:Each planet is shown cut in half at the bottom of its well, with the depth of the well measured down to the planet's ''flat'' surface.
:The planet sizes are to the same scale as the wells. Interplanetary distances are not to scale.
:Depth = (G × PlanetMass) / (g × PlanetRadius)
:G = Newton's constant
:g = 9.81 m/s2

:'''Planetary Descriptions'''
:To Sun, very very far down
:Mercury
:Venus
:Earth - 6379 km [originally 5,478 km]
:Moon - 288 km
:Mars - 1,286 km
:Ganymede
:Io
:Jupiter
::[A drawing of a "very deep" gravity well, "Your mom" at the bottom, several member of "local football team" falling down towards her.]
::Jupiter is not much larger than Saturn, but much more massive. At its size, adding more mass just makes it denser due to the extra squeezing of gravity.
::If you dropped a few dozen more Jupiters into it, the pressure would ignite fusion and make it a star.
:Europa
:Titan
::Two alarms: Weeoooeeoooeeooo
:Saturn
::Rings
:Uranus
:Neptune
::Megan: An even more glorious dawn awaits!

:'''Mars Inset'''
:[Mars gravity well, the Pathfinder probe on its surface, with its moons Deimos and Phobos as smaller gravity wells.]

:[Figure of a man (to scale) in Deimos's gravity well.]
:You could escape Deimos with a bike and a ramp.

:[Figure of a man (to scale) in Phobos's gravity well.]
:A thrown baseball could escape Phobos.

:'''Earth Inset'''
:[Zoomed-in view of Earth/moon gravity well, featuring the relative locations of the atmosphere, Low Earth Orbit, the International Space Station, the Space Shuttle, GPS satellites, and satellites in geosynchronous orbit.]
:Cueball: This is why it took a huge rocket to get to the moon but only a small one to get back.

:It takes the same amount of energy to launch something on an escape trajectory away from Earth as it would to launch it 6,000 km upward under constant 9.81 m/s2 Earth gravity.

:Hence, Earth's well is 6,000 km deep.

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Large drawings]]
[[Category:Charts]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:American football]]
[[Category:Baseball]]
[[Category:Your Mom]]
[[Category:Space]]

681: Gravity Wells

2016-01-27T14:30:38Z

173.245.54.51: /* Transcript */ Added note that Randall corrected an error in the original release.

{{comic
| number = 681
| date = December 28, 2009
| title = Gravity Wells
| image = gravity_wells.png
| titletext = This doesn't take into account the energy imparted by orbital motion (or gravity assists or the Oberth effect), all of which can make it easier to reach outer planets.
}}
{{TOC}}

The xkcd page links to [http://xkcd.com/681_large/ a much larger version].

==Explanation==

The comic shows the gravitational potential (energy transferred per unit mass due to gravity) for the positions of each planet in the solar system -- including some moons and Saturn's rings. An object traveling along an upward slope loses energy, while an object traveling along a downward slope gains energy.

Escaping a planet or moon's orbit requires enough energy (e.g. by walking, jumping, or rocket) to reach the top of either peak that defines the edge of the well. The peak to the left indicates the minimum energy required to exit orbit. The peak to the right indicates the maximum energy required to exit orbit. In order to exit orbit with the minimum amount of energy, you would have to travel towards the center of the solar system; to exit orbit with the maximum amount of energy, you would have to travel away from the center of the solar system (the Sun). In reality, the strength of gravity decreases with distance from the planet. However, a comparison of energy expended to escape the gravitational pull allows for a simpler comparison between the objects.

The height of the graph is scaled to kilometers via the gravitational potential an object has at the given height assuming at a constant acceleration due to Earth's surface gravity. The {{w|Sun|Sun's}} gravity well is not shown in its entirety, but is just indicated on the far left as ''"Very very far down"''. Had it been shown in its full extent it would have made the rest of the drawing so small in comparison that it would have been unreadable. As the gravitational potential increases with distance from the sun the graph has a general upward slope. To rise out of each well on the diagram, and therefore escape the planets gravity, it would require the same energy required to rise out of a physical well of that depth at Earth's surface gravity.

The length of each gravity well is scaled to the diameter of the planet and the spacing between the planets is not to scale with distance from the sun. This is necessary to make the graph readable. Because the distance between the planets are condensed the gravitational potential, from the gravity pulling toward the sun, accumulates quicker. This is the reason for the large peaks between the planets. The moons shown in the chart are at the appropriate distance from their respective planets' gravity wells for their orbits.

Each planet is shown cut in half at the bottom of its well, with the depth of the well measured down to the planet's flat surface.

The Earth's gravity well's depth in the inset and in the main part of the comic don't match. This is most likely a mistake by Randall.

==== Inner Planets ====
* {{w|Mercury_(planet)|Mercury}} -- no facts listed
* {{w|Venus_(planet)|Venus}} -- no facts listedc
* {{w|Earth}} and {{w|Moon}}: The listed depth of the gravity well at Earth was originally listed at 5478 km rather than the correct value of 6379 km seen in the cutout. Randall has since corrected it. The Moon's is 288 km.
* {{w|Mars}}: The listed depth of the gravity well of Mars is 1286 km.

==== Outer Planets ====
* {{w|Jupiter}}: Jupiter is so massive and dense that it is comparable in mass to a {{w|Brown dwarf}} which is the smallest kind of star. Saturn, while similar in size, is composed of much lighter gas material. Hence Saturn's mass and therefore its gravitational pull are much smaller. Had a few dozen times the mass of gasses contained in Jupiter condensed in that location, the gravitational pull would cause the pressure and temperature to increase to a level that is sufficient to ignite {{w|Nuclear fusion|nuclear fusion}}. Had that happen during creation of our solar system, we would have two {{w|Sun|Suns}} and our solar system would be a {{w|Binary system (astronomy)|Binary system}}. Jupiter has {{w|Moons_of_Jupiter|67 moons}} of which 3 are shown;
** {{w|Ganymede_(moon)|Ganymede}} -- moon of Jupiter, no facts given
** {{w|Io_(moon)|Io}} -- moon of Jupiter, no facts given
** {{w|Europa_(moon)|Europa}} -- moon of Jupiter, no facts given

* {{w|Saturn}}: The diagram shows the position of the {{w|rings of Saturn}} in Saturn's gravity well. Saturn's rings start fairly near the planet and extend out quite far, therefore multiple stripes are shown in the figure. The rings are also shown in multiple colors and roughly match the observed colors from photos take by the {{w|Cassini–Huygens|Cassini spacecraft}} expedition as it passed Saturn. All of the colors of the planets and moons represent the predominant color of that object as observed from earth. Saturn has {{w|Moons_of_Saturn|62 moons}} of which one is shown;
** {{w|Titan (moon)|Titan}}, a moon of Saturn. The figures on Titan are sirens, a reference to Kurt Vonnegut's ''{{w|The Sirens of Titan}}''.

* {{w|Uranus}}: Notably absent is any "your-anus" jokes.
* {{w|Neptune}}: Megan's quote is a paraphrase of {{w|Carl Sagan|Carl Sagan's}} quote, "...but from a planet orbiting a star in a distant globular cluster, a still more glorious dawn awaits, not a sun-rise, but a galaxy rise." [http://www.youtube.com/watch?v=zSgiXGELjbc Video here]

==== Cut outs and sketches====
The following items are listed from top to bottom and left to right.

* Mars moons: The Mars cutout shows the Mars moon system, including the moons Deimos and Phobos. The depth of the Mars gravity well is listed at 1286 km.
** {{w|Deimos (moon)|Deimos}}: The gravity on Deimos, a moon of Mars, is so weak that a bike jump would be sufficient to escape its gravity.
** {{w|Phobos (moon)|Phobos}}: The gravity on Phobos, a moon of Mars, is so weak that you could launch a baseball into space simply by throwing it.

* Your mom and a local football team: The sketch next to Jupiter is playing on the classic "Yo Mama" joke. It combines "Yo Mama is so fat" and "Yo Mama is so horny". The sketch implies that she has a huge gravitational pull because she is very fat, and has sex with an entire football team by demonstrating a football team falling into her very deep gravity well. A "Yo Mama" joke also appears in comic [[89: Gravitational Mass]].

* Earth's Moon: The cut out shows the significant difference in strength between the {{w|gravity well}} of the Earth and the Moon. Cueball comments that the {{w|Apollo Lunar Module|Apollo Lunar Module}} was very small and the {{w|Saturn V}} rocket was very large because escaping the Earth's gravity well takes much more energy than escaping the Moon's. The cut out also shows that objects like the {{w|International_Space_Station|International Space Station}}, the {{w|Space shuttle|space shuttle}}, {{w|GPS satellite|GPS satellites}} and {{w|Geostationary orbit|geo-stationary satellites}} at their respective positions within Earth's gravity well. The depth of Earth's gravity well is listed correctly at 6 379 km (note the difference from the non-cutout number). The depth of the Moon's gravity well is listed at 288 km.

=== How to calculate gravity wells ===
The text near the bottom of Jupiter's gravity well explains that the depth of the well is mass-of-planet over radius-of-planet with Newton's constant and 9.81 m/s² as constants, where 9.81 m/s² is the acceleration of a free falling body at Earth's gravity.

The calculation for a gravity well is:
:depth = (G * Planet-mass ) / (9.81 m/s2 * Planet-radius)
::where G is {{w|Isaac_Newton|Newton}}'s {{w|Gravitational_constant|gravitational constant}}, and
::9.81 m/s2 is the {{w|Acceleration|acceleration}} rate of a {{w|Gravity_of_Earth|free falling body on earth}} at sea level (g).

====Title text====
The title text indicates that the planets motion can affect the amount of energy for escape velocity. It is possible to change speed by using the planets orbital speed and gravity. This is know as a performing a slingshot or a {{w|Gravity assist|gravity assist}}, and is done to gain speed or to brake when needed. The use of rocket engines are more effective when used at a high speed slingshot maneuver, which is know as the {{w|Oberth effect}}, where most energy is going into moving the rocket as opposed to moving the exhaust -- conserving the maximum useful energy. On earth the same principle is used when launching rockets. Rockets are always launched in a eastward direction to make maximum use of the rotational energy of the earth. Launching rockets in a westward direction would require significant additional energy. Because of this most artificial satellites are flying east around the globe.

The size of the gravity-well as described in this comic is not accounting for these factors. Therefore leaving the solar system (or any of the gravity wells of the planets) could require less energy than described by the graph, assuming that the launch and slingshots are properly designed and executed.

==== Escape Velocities ====
The following table was adapted from the table in {{w|Escape velocity#List of escape velocities|Escape velocity}}, using ''h'' = ''V_e''^2 / 2''g'':
{| class="wikitable" border="1"
| Location || with respect to || Ve (km/s) || Well depth (km) ||
| Location || with respect to || Ve (km/s) || Solar well (Mm) || Total depth (Mm)
|-
| on the Sun, || the Sun's gravity: || 617.5 || 19,435,000 || || || || || || 19,435
|-
| on Mercury, || Mercury's gravity: || 4.3 || 942 ||
| at Mercury, || the Sun's gravity: || 67.7 || 233.6 || 235
|-
| on Venus, || Venus' gravity: || 10.3 || 5,407 ||
| at Venus, || the Sun's gravity: || 49.5 || 124.9 || 130
|-
| on Earth, || the Earth's gravity: || 11.2 || 6,393 ||
| at the Earth/Moon, || the Sun's gravity: || 42.1 || 90.3 || 97
|-
| on the Moon, || the Moon's gravity: || 2.4 || 294 ||
| at the Moon, || the Earth's gravity: || 1.4 || || 91
|-
| on Mars, || Mars' gravity: || 5 || 1,274 ||
| at Mars, || the Sun's gravity: || 34.1 || 59.3 || 61
|-
| on Jupiter, || Jupiter's gravity: || 59.5 || 180,400 ||
| at Jupiter, || the Sun's gravity: || 18.5 || 17.4 || 198
|-
| on Ganymede, || Ganymede's gravity: || 2.7 || 372 || || || || ||
|-
| on Saturn, || Saturn's gravity: || 35.6 || 64,600 ||
| at Saturn, || the Sun's gravity: || 13.6 || 9.43 || 74
|-
| on Uranus, || Uranus' gravity: || 21.2 || 22,907 ||
| at Uranus, || the Sun's gravity: || 9.6 || 4.7 || 28
|-
| on Neptune, || Neptune's gravity: || 23.6 || 28,400 ||
| at Neptune, || the Sun's gravity: || 7.7 || 3.02 || 31
|-
| on Pluto, || Pluto's gravity: || 1.2 || 73 || || || || ||
|-
|at Solar System galactic radius, || the Milky Way's gravity: || 525 || 14,000
|}

==Transcript==
:'''Main Text'''
:Gravity Wells scaled to Earth surface gravity
:This chart shows the "depth" of various solar system gravity wells.
:Each well is scaled such that rising out of a physical well of that depth — in constant Earth surface gravity — would take the same energy as escaping from that planet's gravity in reality.
:Each planet is shown cut in half at the bottom of its well, with the depth of the well measured down to the planet's ''flat'' surface.
:The planet sizes are to the same scale as the wells. Interplanetary distances are not to scale.
:Depth = (G × PlanetMass) / (g × PlanetRadius)
:G = Newton's constant
:g = 9.81 m/s2

:'''Planetary Descriptions'''
:To Sun, very very far down
:Mercury
:Venus
:Earth - 6379 km [originally 5,478 km]
:Moon - 288 km
:Mars - 1,286 km
:Ganymede
:Io
:Jupiter
::[A drawing of a "very deep" gravity well, "Your mom" at the bottom, several member of "local football team" falling down towards her.]
::Jupiter is not much larger than Saturn, but much more massive. At its size, adding more mass just makes it denser due to the extra squeezing of gravity.
::If you dropped a few dozen more Jupiters into it, the pressure would ignite fusion and make it a star.
:Europa
:Titan
::Two alarms: Weeoooeeoooeeooo
:Saturn
::Rings
:Uranus
:Neptune
::Megan: An even more glorious dawn awaits!

:'''Mars Inset'''
:[Mars gravity well, the Pathfinder probe on its surface, with its moons Deimos and Phobos as smaller gravity wells.]

:[Figure of a man (to scale) in Deimos's gravity well.]
:You could escape Deimos with a bike and a ramp.

:[Figure of a man (to scale) in Phobos's gravity well.]
:A thrown baseball could escape Phobos.

:'''Earth Inset'''
:[Zoomed-in view of Earth/moon gravity well, featuring the relative locations of the atmosphere, Low Earth Orbit, the International Space Station, the Space Shuttle, GPS satellites, and satellites in geosynchronous orbit.]
:Cueball: This is why it took a huge rocket to get to the moon but only a small one to get back.

:It takes the same amount of energy to launch something on an escape trajectory away from Earth as it would to launch it 6,000 km upward under constant 9.81 m/s2 Earth gravity.

:Hence, Earth's well is 6,000 km deep.

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Large drawings]]
[[Category:Charts]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:American football]]
[[Category:Baseball]]
[[Category:Your Mom]]
[[Category:Space]]

Talk:1363: xkcd Phone

2014-05-02T10:09:06Z

173.245.54.51:

Where can i get one of these? :D [[User:UniTrader|UniTrader]] ([[User talk:UniTrader|talk]]) 04:11, 2 May 2014 (UTC)

I'm pretty sure the "scream when falling" thing and the "flightaware" stuff can be done somehow with Tasker. [[Special:Contributions/141.101.103.206|141.101.103.206]] 04:23, 2 May 2014 (UTC)

;Designer?

I suspect it was either Black Hat or Beret Guy, but I'm not sure which. A collaboration? [[Special:Contributions/173.245.54.45|173.245.54.45]] 04:47, 2 May 2014 (UTC)

This sounds like something straight out of aperture. {{unsigned ip|108.162.221.55}}

;Simulates alternate speeds of light

Yes, useless as a feature on all the time; but it would be a cool app. [[User:Markhurd|Mark Hurd]] ([[User talk:Markhurd|talk]]) 05:57, 2 May 2014 (UTC)
:Absolutely. Where can I get an app like that?[[Special:Contributions/108.162.225.157|108.162.225.157]] 06:22, 2 May 2014 (UTC)

'''Changed the speed of light to 2.99x10^8'''

Yeah sorry forgot to login. does anyone know how to do the indices formatting other than eg 2.99x10(littlex) rather then 2.99x10^x? [[User:Jonv4n|Jonv4n]] ([[User talk:Jonv4n|talk]]) 06:29, 2 May 2014 (UTC)
: Whassup? [[Special:Contributions/141.101.89.220|141.101.89.220]] 07:43, 2 May 2014 (UTC)

About the attracting insects ... I would expect this to be normal feature in night. Trapping, however ... -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 09:08, 2 May 2014 (UTC)

'''Siri'''

Could the Siri bit be a reference to Portal? When I first read it, I remembered this GLaDOS quote: "Your Aperture Science Weighted Companion Cube will never threaten to stab you, and in fact cannot speak. If your Weighted Companion Cube does speak, please disregard its advice." Could be completely wrong; just a thought. [[Special:Contributions/173.245.54.51|173.245.54.51]] 10:09, 2 May 2014 (UTC)