explain xkcd - User contributions [en]

1548: 90s Kid

2015-07-09T21:38:21Z

108.162.216.171:

{{comic
| number = 1548
| date = July 8, 2015
| title = 90s Kid
| image = 90s_kid.png
| titletext = We remember Rugrats, and think of them every time our kids look at us through their baby gates.
}}

==Explanation==
This is another example where [[Randall]] describes the inexorable passage of time.

The children are complaining about things their parents tell them, as children are wont to do. Their first complaint is something recognizable, the usual "just eat your vegetables, they're good for you." The second is about a comment "LOL, remember Rugrats and Doug? Share if you're a 90's kid" which, however, is a generic social media comment that a "90's kid" would make, not something you would expect a mother to say. At least not in the context of things their children are embarrassed about. But it illustrates that the  teens and tweens of yesteryear are now adults, and parents at that.

According to the [https://www.cia.gov/library/publications/the-world-factbook/fields/2256.html CIA World Factbook,] in the USA the median age of mothers at their first birth is 25.6 (2011 estimate). On the date this comic was published, this would center the mother's own birth date in very late 1989.

Although there are various interpretations of the term "90's kid," most center around the person in question having had most or all of their childhood during the 1990s. The stereotypical '90s kid has a strong attachment to objects, movies, TV shows, phrases etc from the era of their childhood, which bring back memories of their younger days. In this comic Randall picks up on a number of things which could be used to identify a '90s kid:

*The use of the acronym "{{w|LOL}}" means '''laughing out loud''', or '''laugh out loud''', and was probably coined in the 1980s, finding its way into general usage with the later uptake of wider public Internet and should be known to every kid working or playing on a computer today.

*{{w|Rugrats}} is a cartoon that was produced from 1991 all the way to 2004, featuring the adventures of a group of toddlers and babies.

*{{w|Doug}} is another cartoon that ran for years 1991 to 2000.

*The use of traditional social media, and more specifically of sharing the type of post described.

Given that the children shown in the comic appear to be somewhat older than newborn babies, we can safely assume that the comic is set at some point in the not too distant future.

The title text suggests that viewing a child of one's own peering through such a barrier elicits nostalgia for the Rugrats cartoon. A {{w|baby gate}} is a semi-fixed piece of child-safety equipment to restrict a small child, typically a toddler, from leaving a safe area of a house, and especially to prevent access to stairways (up or down, where falls may happen), without overly inconveniencing an adult who can open the gate. Baby gates, fully enclosed {{w|playpen}}s and similar barriers around cots feature as usually insurmountable barriers to the younger characters in Rugrats, who are of crawling and toddling age.

==Transcript==
:[Two kids, with very different hair style, are in a playground. A fence is visible in the background, and on the ground appear to be various items including a puddle or rug and toy blocks.]
:Scruffy-haired kid: Ugh don't you hate how parents are all "Eat your carrots" and "LOL, remember Rugrats and Doug? Share if you're a 90's kid!"
:[Caption below the panel:]
:'''The median age at first birth in the US is 25, which means the typical new mother is now a 90's kid.'''

{{comic discussion}}

[[Category:Comics to make one feel old]]

Talk:1504: Opportunity

2015-03-27T18:01:09Z

108.162.216.171:

"Everything the light touches is our kingdom" are Mufasa words from 'The Lion King' (1994) --[[User:JakubNarebski|JakubNarebski]] ([[User talk:JakubNarebski|talk]]) 08:39, 27 March 2015 (UTC)
- The "You must never go there" line is also from Lion King. http://www.imdb.com/title/tt0110357/quotes?item=qt0371437 [[User:Drmouse|Drmouse]] ([[User talk:Drmouse|talk]]) 11:40, 27 March 2015 (UTC)

May someone make this Transcritpt better? [[Special:Contributions/141.101.104.10|141.101.104.10]] 08:58, 27 March 2015 (UTC)

Hey, thanks to whoever tidied up my explanation [[Special:Contributions/141.101.98.185|141.101.98.185]] 11:01, 27 March 2015 (UTC)

I think the second line ("We must never go there") is from the same scene in ''The Lion King'' as the first line, not a reference to ''Space Odyssey'' . See [[http://youtu.be/K5lEJlbEgz4]] from 0:52 to 1:23. [[Special:Contributions/108.162.216.55|108.162.216.55]] 11:04, 27 March 2015 (UTC)

It seems to me to be common currency that the 'missing' word in "one small step" is "a", not "this" (whether as a fluffed line, in the moment, or a temporary radio drop-out over that bare syllable). Also, while it's highly ''suggested'', there's no certainty in the title-text that the new Mars-landing quote ''necessarily'' ended in fatality. [[Special:Contributions/141.101.98.192|141.101.98.192]] 14:31, 27 March 2015 (UTC)

I just don't get how the rover could gain more power. It is after all, isolated on mars. All it could do is get weaker. Maybe it was already strong enough to control half of mars. [[User:YourLifeisaLie|The Goyim speaks]] ([[User talk:YourLifeisaLie|talk]]) 15:05, 27 March 2015 (UTC)

I'm surely not the only person who read the title text and thought, "Well, that's more work for the Death of Being Ground by a Mars Rover Rock Abrasion Tool." [[Special:Contributions/108.162.216.171|108.162.216.171]] 18:01, 27 March 2015 (UTC)

1486: Vacuum

2015-02-13T14:38:40Z

108.162.216.171: /* Explanation */

{{comic
| number = 1486
| date = February 13, 2015
| title = Vacuum
| image = vacuum.png
| titletext = Do you think you could actually clean the living room at some point, though?
}}

==Explanation==

According to quantum mechanics there is tremendous energy density in space-time itself: this is known as: {{w|vacuum energy}}, zero point energy, vacuum foam, etc. Of course, this energy is not literally available to be tapped although it does {{w|Hawking radiation|evaporate}} off {{w|black hole}}s (see the “What If?” released the same week as this comic: [http://what-if.xkcd.com/129/ Black Hole Moon]).

In the cartoon, [[Beret Guy]] appears to be making a silly mistake, confusing the metaphorical »vacuum« referred to in calculations of the theoretical energy density of space time{{Citation needed}} with the partial vacuum of a {{w|vacuum cleaner}} – a device commonly used to clean dust from households.

[[Cueball]] tries to correct him, but it turns out that Beret Guy really is able to tap into this fundamental source of energy.

But even though Beret Guy now claims the Universe is his to command, (a sentence used by the crazy villain in many movies), Cueball is not fazed by this and simply asks, in the title text, if Beret Guy would use the vacuum for it's intended purpose and clean the living room.

==Transcript==
:[Beret guy is holding an upright vacuum cleaner upside-down by the handle, waving it around above his head]

:[The vacuum cleaner is upright on the ground, and Beret guy is standing on its body, wiggling the handle]
:Cueball: What are you doing?
:Beret Guy: Trying to unlock the tremendous energy of the vacuum.

:[Beret guy rides the vacuum cleaner as it begins to lift off, propelled upward by an unknown force]
:Cueball: That's not what that -
:Beret Guy: '''Ha ha! It works!'''

:[Beret guy flies away on the vacuum cleaner]
:Cueball: I '''said''', that's -
:Beret Guy: The universe is mine to command!!

{{comic discussion}}

[[Category:Comics featuring Beret Guy]]
[[Category:Comics featuring Cueball]]

Talk:1461: Payloads

2014-12-19T14:30:39Z

108.162.216.171:

It's possible he's talking about [http://poorlydrawnlines.com/comic/earth-and-moon/ this comic].
[[Special:Contributions/108.162.249.203|108.162.249.203]] 07:20, 17 December 2014 (UTC)

I think he used horses as a reference to the unit of work, horse power, but in this case instead of being the 550 foot pounds per second, it is the force required to put a horse at that altitude
[[Special:Contributions/199.27.128.195|199.27.128.195]] 08:10, 17 December 2014 (UTC)
:The top one clearly says "Spacecraft mass" and the bottom says "Capacity" (which is normally either the mass or volume something can hold), so I don't think either refers to force. [[Special:Contributions/173.245.54.175|173.245.54.175]] 08:32, 17 December 2014 (UTC)

Horses might also be used as a length unit... I am wondering if this is somehow related to the size of SRBs [http://www.snopes.com/history/american/gauge.asp] ;-) {{unsigned|Ld75}}
:There is the famous tail (no pun intended) of how the width of the Space Shuttles SRBs are related to the width of a horses, er, um, butt -- which apparently is not true. However, similarly to the "Upgoer Five", Randall may just be trying to relate a very difficult to grasp concept (weight of a huge object) to something that with which a large number of people may be familiar. [[User:Jarod997|Jarod997]] ([[User talk:Jarod997|talk]]) 14:34, 17 December 2014 (UTC)

A few mass calculations: (All masses from wikipedia)

* ISS - 450,000 kg / 932 Horses = 483 kg/Horse
* Skylab - 77,088 kg / 171 Horses = 450 kg/Horse
* Mir - 129,700 kg / 286 Horses = 453 kg/Horse
* Shuttle Payload - 24,400 kg / 54 Horses = 452 kg/Horse
* Compton GRO - 17,000 kg / 38 Horses = 447 kg/Horse

It looks like Randall probably used 450kg as a standard horse, which seems like a fairly average weight for a {{w|Horse#Size and Measurement|horse}}. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 09:06, 17 December 2014 (UTC)

Curious: the Atlas-Centaur rocket is listed as lifting Centaurs, not horses. [[Special:Contributions/141.101.98.244|141.101.98.244]] 09:11, 17 December 2014 (UTC)

:Plus the Pegasus rocket is labelled as lifting one (mythical, horse-sized?) Pegasus. I took this as synchronicity, but currently someone (who missed the Centaur reference in the part of the main text about "joke additions/deviations") who edited the the main text seems to think that it's purely a mythical reference. [[Special:Contributions/141.101.98.245|141.101.98.245]] 13:27, 17 December 2014 (UTC)

The Keyhole captions are wrong; assuming 450 kg/horse, 40 horses for the [[wikipedia:KH-7 Gambit|Keyhole 7]] would be around 18,000 kg. Documents declassified a couple of years ago give the mass as around 2,000 kg. The [[wikipedia:Corona (satellite)|Keyhole 3]] was even smaller. The mass and dates are about right for [[wikipedia:KH-11 Kennan|Keyhole 11]] satellites but I don't know where the 3 and 7 have come from (the dates are wrong for the third and seventh Keyhole 11s) [[Special:Contributions/141.101.99.85|141.101.99.85]] 09:43, 17 December 2014 (UTC)

Initially I thought that the position of 'T Rex' along the X axis (approx 1985) may be a link to the band {{w|T. Rex (band)|T.Rex}}, but according to wiki that was 1967-1977. I guess it could be a random date, but thats not usually Randall's style... --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 10:51, 17 December 2014 (UTC)
:The T Rex "Sue" was discovered in August 1990. Not quite right, either. [[Special:Contributions/108.162.250.214|108.162.250.214]] 11:10, 17 December 2014 (UTC)
::Perhaps a reference to the date of 'Jurassic Park'? Not sure exactly when that came out but I think it's in the right range. [[Special:Contributions/108.162.238.189|108.162.238.189]] 14:55, 17 December 2014 (UTC)
:::Hadn't thought of that.. Though after checking, {{w|Jurassic Park}} was released 1993, and I believe set in 1990. Still doesn't seem to tie up.. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 15:22, 17 December 2014 (UTC)
::::I never knew there was ever a space craft called "T-Rex". Learn something new everyday! ;) {{unsigned|Dangerkeith3000}}

The Oldsmobile is probably a reference to the movie ''{{w|Mom and Dad Save the World}}''. The title characters' station wagon was from around that era -- and it ''did'' go into space in the movie. --[[User:Aaron of Mpls|Aaron of Mpls]] ([[User talk:Aaron of Mpls|talk]]) 11:47, 17 December 2014 (UTC)

'''Terrastar''' may be referring to [[wikipedia:TerreStar-1|TerreStar-1]], with a launch mass of 6,910 kg, divided by 15 horses is about 460 kg/Horse. This is consistent with the above calculations. [[User:Jarod997|Jarod997]] ([[User talk:Jarod997|talk]]) 14:23, 17 December 2014 (UTC)
:Based on that and its accurate position on the X axis, I would agree with you. I've added it to the table, with a note below. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 14:38, 17 December 2014 (UTC)

'''Thor''' may be referring to the [[wikipedia:Thor-Able|Thor-Able]] launch vehicle. First flight of 1958 (good position on the graph), and payload of 120 kg is about 40 kg / dog -- that's a bit high for an average, but depending on the breed it could be accurate. [[User:Jarod997|Jarod997]] ([[User talk:Jarod997|talk]]) 14:58, 17 December 2014 (UTC)
:Yes, I believe that is correct. Added to tables. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 15:22, 17 December 2014 (UTC)

Based on horse payload, location on X-axis (time of first launch?), and some general wikipedia browsing, I believe the unlabeled launch vehicle on the bottom is a Delta IV Medium. According to Wikipedia, it was first launched on 11 March 2003, which fits the location on the timeline. It had an LEO payload capacity of 9,420 kg, which equates to 20.9333333 horses at the estimation of 450kg/horse. For reference, all my information was pulled from http://en.wikipedia.org/wiki/Delta_IV#Delta_IV_Medium. [[User:Screamsquad|Screamsquad]] ([[User talk:Screamsquad|talk]]) 16:20, 17 December 2014 (UTC)
:Certainly seems a likely candidate..--[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 17:08, 17 December 2014 (UTC)

;Title Text Calcs

I did some calculations on the title text, though I'm not sure how correct they are. We can use our standard horse at 450kg, and assuming 9.81m/s2 gravity (neglecting the slight drop in gravity as it moves up the space elevator), the formula I've used is:

<pre>1 Watt = 1 Newton raised 1 Metre in 1 Sec
Power[Watts] = (450[kg] * 9.81[m/s2]) * LEO[m] / Time[s]</pre>

A large power station is a pretty vague measure, but I would guess we are looking at around 1GW. I found a 30 acre solar farm (in the not-so-sunny UK) with an output of 5MW, scaled linearly (which may well not be valid) a 0.6 acre (2500m2 back yard could yield 93.5kW. Using these power guesstimates, we can calculate the altitude at which the 500 horses/year and 10 horses/minute converge. It works out at roughly 1350km. Depending on where you look, LEO is [https://www.google.com/search?q=Low+earth+orbit&rls=com.microsoft%3Aen-gb%3AIE-SearchBox&oe=UTF-8&gfe_rd=cr&gws_rd=ssl&oq=&gs_l= classified as anything under 2000km].

Now I know there are a lot of assumptions in there, and really the whole formula is backwards, but hey... its a starting point! --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 17:05, 17 December 2014 (UTC)

I think Randall may have been talking to Andrew Hussie --[[Special:Contributions/141.101.106.89|141.101.106.89]] 21:50, 17 December 2014 (UTC)

https://what-if.xkcd.com/58/
Getting to space is easy, staying in space is hard.

The energy required to get to 100km, briefly, is about 1 MJ/kg
The energy required to stay in low earth orbit is a bit over 30 MJ/kg

It's tricky to get to low earth orbit with a space elevator, you can go up 200km, but as soon as you let go of the elevator you come down. If you put enough mass at 200km the whole elevator comes down. Not sure which number to use, but I'd go with the 30 MJ/kg, or 15 GJ/horse. So the solar array is about 240kW (averaged over the whole year) and the power plant is 2.5GW. This looks a bit high so maybe the horses don't stay in orbit.

--[[Special:Contributions/108.162.219.248|108.162.219.248]] 15:49, 18 December 2014 (UTC)

:It depends on what he means by launch I suppose. I had simply looked at getting to LEO altitude, but staying there once you let go of the cable is a whole different ball game. I believe the only way to get into orbit from a space elevator (lacking additional power) is to go right to geostationary height? Let go anywhere under that altitude and you go into orbital decay.

:Out of interest, where did you get the 1MJ/kg and 30MJ/kg values? As far as power stations, the new generation twin reactor {{w|Hinkley Point C nuclear power station}} (only know that one because its local to me) is designed to output 3.2GW, so 2.5GW isn't over the top. I would say that 240kW for aback yard solar farm is pretty large, depending on your location and size of back yard. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 17:11, 18 December 2014 (UTC)

::1MJ/kg comes from mgh for 1kg at 100km we get 9.81 * 100,000 
::30MJ/kg comes from 1/2 mv^2 I happen to know that orbital velocity is about 8km/s so 1/2*8000^2 = 32,000,000

::Normally I'd say close enough for goverment work, but in this case NASA probably uses a bit more precision. If you want to be more precision, visit wikipedia "specific orbital energy" and "circular orbit".

::If we release a horse from the space elevator at any altitude it will be in orbit, at least until it contacts the earth's atmosphere. It turns out that if we release it at 30,000km (from the earths center = 23,600km altitude) then at perigee the altitude is 100km. High enough that a horse would stay in orbit for a while. Releasing 750 km higher raises perigee to 1000km altitude. So we don't have to go all the way to geostationary orbit, just high enough. But still 23,000km is not LEO.

::--[[Special:Contributions/108.162.219.248|108.162.219.248]] 04:32, 19 December 2014 (UTC)

:::Ok, I'm just about following you I think! So assuming we are launching to orbit, we have to get to 23,600km, at which point gravity is considerably reduced. We definately have to take into account {{w|Space elevator#Apparent gravitational field|change in gravity}} as our horses move up the cable.

:::I did some maths, and I believe it takes 19.9GJ to get a 450kg horse to 23,600km. That is essentially mgh, but taking into account the change in gravity. At 1 Watt, thats gonna take 631 years. Our 500 horses per year solar plant needs to output 315kW ([http://www.solardaily.com/reports/Independence_Solar_Completes_300_kW_Rooftop_Solar_Array_999.html 300kW solar array on a roof for reference]). Our 10 horses per minute power station would need to output 3.32GW, so a decent nuclear facility. Once the Three Gorges Dam in China is running at full capacity (22.5GW), it could be launching 68 horses per minute. Running constantly at full capacity, we could rid the world of horses (est 58 million) in under two years. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 11:09, 19 December 2014 (UTC)

I filled out the remaining fields. I thought about getting the interior capacities of all 1981 Oldsmobile models but doesn't seem worth it. It's clearly a joke so that kind of research doesn't seem necessary.{{unsigned ip|173.245.56.152}}

'''Arrow of Time'''
Did anyone else notice the special advert for Xmas gifts? It was up at the top of the main xkcd page yesterday 2014-December-17, but gone today (the 18th). In black, blue and red colored printing it said:
----
"The XKCD store Christmas shipping deadline is Friday! 
Once it passes, there is no going back. The arrow of time drags us all 
inexorably forward toward decay and disorder toward the end of all things. 
Toward the empty silence of the grave. ORDER NOW!"
----
I thought it was amusing and saved a bitmap. Was kind of surprised that there was no other mention of this here, or on the fora either. {{unsigned ip|108.162.216.171}}

:I did notice it too, though I've always been a bit disappointed by the limited range of T-shirt comics. None of my favourites are on there. As far as this page mentioning it, it isn't relevant to the comic, so doesn't belong on this page. I don't know of a page on explainxkcd where it would really fit in. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 11:18, 19 December 2014 (UTC)

::Why not make your own? Here is a fridge magnet, it wasn't too hard to figure out the design tools, [http://www.cafepress.com/cp/customize/product2.aspx?from=CustomDesigner&number=1027311439 Duty Calls magnet] Actual size is a little over 2" x 3" (50 x 75mm)--one problem with the design tools is figuring out the final size for some items. Based on my understanding of the CC license, I have not sold these, but I have given a few to friends. Edit--when something I want is in the XKCD store, of course I buy it there so Randall gets the cash. For example, the large poster sized version of Money on the wall in front of me now came from the XKCD store. It would be really cool if Randall made this fridge magnet (or something similar) available on his site.{{unsigned ip|‎108.162.216.171}}

:::I guess part of the reason is that I like the idea of Randall getting the cash from my purchase. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 14:04, 19 December 2014 (UTC)

----
Actually, I find it strange that no explicit mention of Laika or Sputnik 2 is made. --[[Special:Contributions/141.101.75.89|141.101.75.89]] 23:50, 18 December 2014 (UTC)

I'm pretty sure this has nothing to do with dimensional analysis. Who wrote that part? have you ever actually done dimensional analysis? He's just using a nonstandard unit of measure. Unit conversion is almost -but not entirely- unlike dimensional analysis. {{unsigned ip|108.162.241.5}}

Talk:1461: Payloads

2014-12-19T13:40:55Z

108.162.216.171:

It's possible he's talking about [http://poorlydrawnlines.com/comic/earth-and-moon/ this comic].
[[Special:Contributions/108.162.249.203|108.162.249.203]] 07:20, 17 December 2014 (UTC)

I think he used horses as a reference to the unit of work, horse power, but in this case instead of being the 550 foot pounds per second, it is the force required to put a horse at that altitude
[[Special:Contributions/199.27.128.195|199.27.128.195]] 08:10, 17 December 2014 (UTC)
:The top one clearly says "Spacecraft mass" and the bottom says "Capacity" (which is normally either the mass or volume something can hold), so I don't think either refers to force. [[Special:Contributions/173.245.54.175|173.245.54.175]] 08:32, 17 December 2014 (UTC)

Horses might also be used as a length unit... I am wondering if this is somehow related to the size of SRBs [http://www.snopes.com/history/american/gauge.asp] ;-) {{unsigned|Ld75}}
:There is the famous tail (no pun intended) of how the width of the Space Shuttles SRBs are related to the width of a horses, er, um, butt -- which apparently is not true. However, similarly to the "Upgoer Five", Randall may just be trying to relate a very difficult to grasp concept (weight of a huge object) to something that with which a large number of people may be familiar. [[User:Jarod997|Jarod997]] ([[User talk:Jarod997|talk]]) 14:34, 17 December 2014 (UTC)

A few mass calculations: (All masses from wikipedia)

* ISS - 450,000 kg / 932 Horses = 483 kg/Horse
* Skylab - 77,088 kg / 171 Horses = 450 kg/Horse
* Mir - 129,700 kg / 286 Horses = 453 kg/Horse
* Shuttle Payload - 24,400 kg / 54 Horses = 452 kg/Horse
* Compton GRO - 17,000 kg / 38 Horses = 447 kg/Horse

It looks like Randall probably used 450kg as a standard horse, which seems like a fairly average weight for a {{w|Horse#Size and Measurement|horse}}. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 09:06, 17 December 2014 (UTC)

Curious: the Atlas-Centaur rocket is listed as lifting Centaurs, not horses. [[Special:Contributions/141.101.98.244|141.101.98.244]] 09:11, 17 December 2014 (UTC)

:Plus the Pegasus rocket is labelled as lifting one (mythical, horse-sized?) Pegasus. I took this as synchronicity, but currently someone (who missed the Centaur reference in the part of the main text about "joke additions/deviations") who edited the the main text seems to think that it's purely a mythical reference. [[Special:Contributions/141.101.98.245|141.101.98.245]] 13:27, 17 December 2014 (UTC)

The Keyhole captions are wrong; assuming 450 kg/horse, 40 horses for the [[wikipedia:KH-7 Gambit|Keyhole 7]] would be around 18,000 kg. Documents declassified a couple of years ago give the mass as around 2,000 kg. The [[wikipedia:Corona (satellite)|Keyhole 3]] was even smaller. The mass and dates are about right for [[wikipedia:KH-11 Kennan|Keyhole 11]] satellites but I don't know where the 3 and 7 have come from (the dates are wrong for the third and seventh Keyhole 11s) [[Special:Contributions/141.101.99.85|141.101.99.85]] 09:43, 17 December 2014 (UTC)

Initially I thought that the position of 'T Rex' along the X axis (approx 1985) may be a link to the band {{w|T. Rex (band)|T.Rex}}, but according to wiki that was 1967-1977. I guess it could be a random date, but thats not usually Randall's style... --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 10:51, 17 December 2014 (UTC)
:The T Rex "Sue" was discovered in August 1990. Not quite right, either. [[Special:Contributions/108.162.250.214|108.162.250.214]] 11:10, 17 December 2014 (UTC)
::Perhaps a reference to the date of 'Jurassic Park'? Not sure exactly when that came out but I think it's in the right range. [[Special:Contributions/108.162.238.189|108.162.238.189]] 14:55, 17 December 2014 (UTC)
:::Hadn't thought of that.. Though after checking, {{w|Jurassic Park}} was released 1993, and I believe set in 1990. Still doesn't seem to tie up.. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 15:22, 17 December 2014 (UTC)
::::I never knew there was ever a space craft called "T-Rex". Learn something new everyday! ;) {{unsigned|Dangerkeith3000}}

The Oldsmobile is probably a reference to the movie ''{{w|Mom and Dad Save the World}}''. The title characters' station wagon was from around that era -- and it ''did'' go into space in the movie. --[[User:Aaron of Mpls|Aaron of Mpls]] ([[User talk:Aaron of Mpls|talk]]) 11:47, 17 December 2014 (UTC)

'''Terrastar''' may be referring to [[wikipedia:TerreStar-1|TerreStar-1]], with a launch mass of 6,910 kg, divided by 15 horses is about 460 kg/Horse. This is consistent with the above calculations. [[User:Jarod997|Jarod997]] ([[User talk:Jarod997|talk]]) 14:23, 17 December 2014 (UTC)
:Based on that and its accurate position on the X axis, I would agree with you. I've added it to the table, with a note below. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 14:38, 17 December 2014 (UTC)

'''Thor''' may be referring to the [[wikipedia:Thor-Able|Thor-Able]] launch vehicle. First flight of 1958 (good position on the graph), and payload of 120 kg is about 40 kg / dog -- that's a bit high for an average, but depending on the breed it could be accurate. [[User:Jarod997|Jarod997]] ([[User talk:Jarod997|talk]]) 14:58, 17 December 2014 (UTC)
:Yes, I believe that is correct. Added to tables. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 15:22, 17 December 2014 (UTC)

Based on horse payload, location on X-axis (time of first launch?), and some general wikipedia browsing, I believe the unlabeled launch vehicle on the bottom is a Delta IV Medium. According to Wikipedia, it was first launched on 11 March 2003, which fits the location on the timeline. It had an LEO payload capacity of 9,420 kg, which equates to 20.9333333 horses at the estimation of 450kg/horse. For reference, all my information was pulled from http://en.wikipedia.org/wiki/Delta_IV#Delta_IV_Medium. [[User:Screamsquad|Screamsquad]] ([[User talk:Screamsquad|talk]]) 16:20, 17 December 2014 (UTC)
:Certainly seems a likely candidate..--[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 17:08, 17 December 2014 (UTC)

;Title Text Calcs

I did some calculations on the title text, though I'm not sure how correct they are. We can use our standard horse at 450kg, and assuming 9.81m/s2 gravity (neglecting the slight drop in gravity as it moves up the space elevator), the formula I've used is:

<pre>1 Watt = 1 Newton raised 1 Metre in 1 Sec
Power[Watts] = (450[kg] * 9.81[m/s2]) * LEO[m] / Time[s]</pre>

A large power station is a pretty vague measure, but I would guess we are looking at around 1GW. I found a 30 acre solar farm (in the not-so-sunny UK) with an output of 5MW, scaled linearly (which may well not be valid) a 0.6 acre (2500m2 back yard could yield 93.5kW. Using these power guesstimates, we can calculate the altitude at which the 500 horses/year and 10 horses/minute converge. It works out at roughly 1350km. Depending on where you look, LEO is [https://www.google.com/search?q=Low+earth+orbit&rls=com.microsoft%3Aen-gb%3AIE-SearchBox&oe=UTF-8&gfe_rd=cr&gws_rd=ssl&oq=&gs_l= classified as anything under 2000km].

Now I know there are a lot of assumptions in there, and really the whole formula is backwards, but hey... its a starting point! --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 17:05, 17 December 2014 (UTC)

I think Randall may have been talking to Andrew Hussie --[[Special:Contributions/141.101.106.89|141.101.106.89]] 21:50, 17 December 2014 (UTC)

https://what-if.xkcd.com/58/
Getting to space is easy, staying in space is hard.

The energy required to get to 100km, briefly, is about 1 MJ/kg
The energy required to stay in low earth orbit is a bit over 30 MJ/kg

It's tricky to get to low earth orbit with a space elevator, you can go up 200km, but as soon as you let go of the elevator you come down. If you put enough mass at 200km the whole elevator comes down. Not sure which number to use, but I'd go with the 30 MJ/kg, or 15 GJ/horse. So the solar array is about 240kW (averaged over the whole year) and the power plant is 2.5GW. This looks a bit high so maybe the horses don't stay in orbit.

--[[Special:Contributions/108.162.219.248|108.162.219.248]] 15:49, 18 December 2014 (UTC)

:It depends on what he means by launch I suppose. I had simply looked at getting to LEO altitude, but staying there once you let go of the cable is a whole different ball game. I believe the only way to get into orbit from a space elevator (lacking additional power) is to go right to geostationary height? Let go anywhere under that altitude and you go into orbital decay.

:Out of interest, where did you get the 1MJ/kg and 30MJ/kg values? As far as power stations, the new generation twin reactor {{w|Hinkley Point C nuclear power station}} (only know that one because its local to me) is designed to output 3.2GW, so 2.5GW isn't over the top. I would say that 240kW for aback yard solar farm is pretty large, depending on your location and size of back yard. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 17:11, 18 December 2014 (UTC)

::1MJ/kg comes from mgh for 1kg at 100km we get 9.81 * 100,000 
::30MJ/kg comes from 1/2 mv^2 I happen to know that orbital velocity is about 8km/s so 1/2*8000^2 = 32,000,000

::Normally I'd say close enough for goverment work, but in this case NASA probably uses a bit more precision. If you want to be more precision, visit wikipedia "specific orbital energy" and "circular orbit".

::If we release a horse from the space elevator at any altitude it will be in orbit, at least until it contacts the earth's atmosphere. It turns out that if we release it at 30,000km (from the earths center = 23,600km altitude) then at perigee the altitude is 100km. High enough that a horse would stay in orbit for a while. Releasing 750 km higher raises perigee to 1000km altitude. So we don't have to go all the way to geostationary orbit, just high enough. But still 23,000km is not LEO.

::--[[Special:Contributions/108.162.219.248|108.162.219.248]] 04:32, 19 December 2014 (UTC)

:::Ok, I'm just about following you I think! So assuming we are launching to orbit, we have to get to 23,600km, at which point gravity is considerably reduced. We definately have to take into account {{w|Space elevator#Apparent gravitational field|change in gravity}} as our horses move up the cable.

:::I did some maths, and I believe it takes 19.9GJ to get a 450kg horse to 23,600km. That is essentially mgh, but taking into account the change in gravity. At 1 Watt, thats gonna take 631 years. Our 500 horses per year solar plant needs to output 315kW ([http://www.solardaily.com/reports/Independence_Solar_Completes_300_kW_Rooftop_Solar_Array_999.html 300kW solar array on a roof for reference]). Our 10 horses per minute power station would need to output 3.32GW, so a decent nuclear facility. Once the Three Gorges Dam in China is running at full capacity (22.5GW), it could be launching 68 horses per minute. Running constantly at full capacity, we could rid the world of horses (est 58 million) in under two years. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 11:09, 19 December 2014 (UTC)

I filled out the remaining fields. I thought about getting the interior capacities of all 1981 Oldsmobile models but doesn't seem worth it. It's clearly a joke so that kind of research doesn't seem necessary.{{unsigned ip|173.245.56.152}}

'''Arrow of Time'''
Did anyone else notice the special advert for Xmas gifts? It was up at the top of the main xkcd page yesterday 2014-December-17, but gone today (the 18th). In black, blue and red colored printing it said:
----
"The XKCD store Christmas shipping deadline is Friday! 
Once it passes, there is no going back. The arrow of time drags us all 
inexorably forward toward decay and disorder toward the end of all things. 
Toward the empty silence of the grave. ORDER NOW!"
----
I thought it was amusing and saved a bitmap. Was kind of surprised that there was no other mention of this here, or on the fora either. {{unsigned ip|108.162.216.171}}

:I did notice it too, though I've always been a bit disappointed by the limited range of T-shirt comics. None of my favourites are on there. As far as this page mentioning it, it isn't relevant to the comic, so doesn't belong on this page. I don't know of a page on explainxkcd where it would really fit in. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 11:18, 19 December 2014 (UTC)

:Why not make your own? Here is a fridge magnet, it wasn't too hard to figure out the design tools, [http://www.cafepress.com/cp/customize/product2.aspx?from=CustomDesigner&number=1027311439 Duty Calls magnet] Actual size is a little over 2" x 3" (50 x 75mm)--one problem with the design tools is figuring out the final size for some items. Based on my understanding of the CC license, I have not sold these, but I have given a few to friends.

----
Actually, I find it strange that no explicit mention of Laika or Sputnik 2 is made. --[[Special:Contributions/141.101.75.89|141.101.75.89]] 23:50, 18 December 2014 (UTC)

I'm pretty sure this has nothing to do with dimensional analysis. Who wrote that part? have you ever actually done dimensional analysis? He's just using a nonstandard unit of measure. Unit conversion is almost -but not entirely- unlike dimensional analysis. {{unsigned ip|108.162.241.5}}

Talk:1461: Payloads

2014-12-18T22:58:15Z

108.162.216.171: ...the arrow of time... Christmas shopping deadline.

It's possible he's talking about [http://poorlydrawnlines.com/comic/earth-and-moon/ this comic].
[[Special:Contributions/108.162.249.203|108.162.249.203]] 07:20, 17 December 2014 (UTC)

I think he used horses as a reference to the unit of work, horse power, but in this case instead of being the 550 foot pounds per second, it is the force required to put a horse at that altitude
[[Special:Contributions/199.27.128.195|199.27.128.195]] 08:10, 17 December 2014 (UTC)
:The top one clearly says "Spacecraft mass" and the bottom says "Capacity" (which is normally either the mass or volume something can hold), so I don't think either refers to force. [[Special:Contributions/173.245.54.175|173.245.54.175]] 08:32, 17 December 2014 (UTC)

Horses might also be used as a length unit... I am wondering if this is somehow related to the size of SRBs [http://www.snopes.com/history/american/gauge.asp] ;-) {{unsigned|Ld75}}
:There is the famous tail (no pun intended) of how the width of the Space Shuttles SRBs are related to the width of a horses, er, um, butt -- which apparently is not true. However, similarly to the "Upgoer Five", Randall may just be trying to relate a very difficult to grasp concept (weight of a huge object) to something that with which a large number of people may be familiar. [[User:Jarod997|Jarod997]] ([[User talk:Jarod997|talk]]) 14:34, 17 December 2014 (UTC)

A few mass calculations: (All masses from wikipedia)

* ISS - 450,000 kg / 932 Horses = 483 kg/Horse
* Skylab - 77,088 kg / 171 Horses = 450 kg/Horse
* Mir - 129,700 kg / 286 Horses = 453 kg/Horse
* Shuttle Payload - 24,400 kg / 54 Horses = 452 kg/Horse
* Compton GRO - 17,000 kg / 38 Horses = 447 kg/Horse

It looks like Randall probably used 450kg as a standard horse, which seems like a fairly average weight for a {{w|Horse#Size and Measurement|horse}}. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 09:06, 17 December 2014 (UTC)

Curious: the Atlas-Centaur rocket is listed as lifting Centaurs, not horses. [[Special:Contributions/141.101.98.244|141.101.98.244]] 09:11, 17 December 2014 (UTC)

:Plus the Pegasus rocket is labelled as lifting one (mythical, horse-sized?) Pegasus. I took this as synchronicity, but currently someone (who missed the Centaur reference in the part of the main text about "joke additions/deviations") who edited the the main text seems to think that it's purely a mythical reference. [[Special:Contributions/141.101.98.245|141.101.98.245]] 13:27, 17 December 2014 (UTC)

The Keyhole captions are wrong; assuming 450 kg/horse, 40 horses for the [[wikipedia:KH-7 Gambit|Keyhole 7]] would be around 18,000 kg. Documents declassified a couple of years ago give the mass as around 2,000 kg. The [[wikipedia:Corona (satellite)|Keyhole 3]] was even smaller. The mass and dates are about right for [[wikipedia:KH-11 Kennan|Keyhole 11]] satellites but I don't know where the 3 and 7 have come from (the dates are wrong for the third and seventh Keyhole 11s) [[Special:Contributions/141.101.99.85|141.101.99.85]] 09:43, 17 December 2014 (UTC)

Initially I thought that the position of 'T Rex' along the X axis (approx 1985) may be a link to the band {{w|T. Rex (band)|T.Rex}}, but according to wiki that was 1967-1977. I guess it could be a random date, but thats not usually Randall's style... --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 10:51, 17 December 2014 (UTC)
:The T Rex "Sue" was discovered in August 1990. Not quite right, either. [[Special:Contributions/108.162.250.214|108.162.250.214]] 11:10, 17 December 2014 (UTC)
::Perhaps a reference to the date of 'Jurassic Park'? Not sure exactly when that came out but I think it's in the right range. [[Special:Contributions/108.162.238.189|108.162.238.189]] 14:55, 17 December 2014 (UTC)
:::Hadn't thought of that.. Though after checking, {{w|Jurassic Park}} was released 1993, and I believe set in 1990. Still doesn't seem to tie up.. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 15:22, 17 December 2014 (UTC)
::::I never knew there was ever a space craft called "T-Rex". Learn something new everyday! ;) {{unsigned|Dangerkeith3000}}

The Oldsmobile is probably a reference to the movie ''{{w|Mom and Dad Save the World}}''. The title characters' station wagon was from around that era -- and it ''did'' go into space in the movie. --[[User:Aaron of Mpls|Aaron of Mpls]] ([[User talk:Aaron of Mpls|talk]]) 11:47, 17 December 2014 (UTC)

'''Terrastar''' may be referring to [[wikipedia:TerreStar-1|TerreStar-1]], with a launch mass of 6,910 kg, divided by 15 horses is about 460 kg/Horse. This is consistent with the above calculations. [[User:Jarod997|Jarod997]] ([[User talk:Jarod997|talk]]) 14:23, 17 December 2014 (UTC)
:Based on that and its accurate position on the X axis, I would agree with you. I've added it to the table, with a note below. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 14:38, 17 December 2014 (UTC)

'''Thor''' may be referring to the [[wikipedia:Thor-Able|Thor-Able]] launch vehicle. First flight of 1958 (good position on the graph), and payload of 120 kg is about 40 kg / dog -- that's a bit high for an average, but depending on the breed it could be accurate. [[User:Jarod997|Jarod997]] ([[User talk:Jarod997|talk]]) 14:58, 17 December 2014 (UTC)
:Yes, I believe that is correct. Added to tables. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 15:22, 17 December 2014 (UTC)

Based on horse payload, location on X-axis (time of first launch?), and some general wikipedia browsing, I believe the unlabeled launch vehicle on the bottom is a Delta IV Medium. According to Wikipedia, it was first launched on 11 March 2003, which fits the location on the timeline. It had an LEO payload capacity of 9,420 kg, which equates to 20.9333333 horses at the estimation of 450kg/horse. For reference, all my information was pulled from http://en.wikipedia.org/wiki/Delta_IV#Delta_IV_Medium. [[User:Screamsquad|Screamsquad]] ([[User talk:Screamsquad|talk]]) 16:20, 17 December 2014 (UTC)
:Certainly seems a likely candidate..--[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 17:08, 17 December 2014 (UTC)

;Title Text Calcs

I did some calculations on the title text, though I'm not sure how correct they are. We can use our standard horse at 450kg, and assuming 9.81m/s2 gravity (neglecting the slight drop in gravity as it moves up the space elevator), the formula I've used is:

<pre>1 Watt = 1 Newton raised 1 Metre in 1 Sec
Power[Watts] = (450[kg] * 9.81[m/s2]) * LEO[m] / Time[s]</pre>

A large power station is a pretty vague measure, but I would guess we are looking at around 1GW. I found a 30 acre solar farm (in the not-so-sunny UK) with an output of 5MW, scaled linearly (which may well not be valid) a 0.6 acre (2500m2 back yard could yield 93.5kW. Using these power guesstimates, we can calculate the altitude at which the 500 horses/year and 10 horses/minute converge. It works out at roughly 1350km. Depending on where you look, LEO is [https://www.google.com/search?q=Low+earth+orbit&rls=com.microsoft%3Aen-gb%3AIE-SearchBox&oe=UTF-8&gfe_rd=cr&gws_rd=ssl&oq=&gs_l= classified as anything under 2000km].

Now I know there are a lot of assumptions in there, and really the whole formula is backwards, but hey... its a starting point! --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 17:05, 17 December 2014 (UTC)

I think Randall may have been talking to Andrew Hussie --[[Special:Contributions/141.101.106.89|141.101.106.89]] 21:50, 17 December 2014 (UTC)

https://what-if.xkcd.com/58/
Getting to space is easy, staying in space is hard.

The energy required to get to 100km, briefly, is about 1 MJ/kg
The energy required to stay in low earth orbit is a bit over 30 MJ/kg

It's tricky to get to low earth orbit with a space elevator, you can go up 200km, but as soon as you let go of the elevator you come down. If you put enough mass at 200km the whole elevator comes down. Not sure which number to use, but I'd go with the 30 MJ/kg, or 15 GJ/horse. So the solar array is about 240kW (averaged over the whole year) and the power plant is 2.5GW. This looks a bit high so maybe the horses don't stay in orbit.

--[[Special:Contributions/108.162.219.248|108.162.219.248]] 15:49, 18 December 2014 (UTC)

It depends on what he means by launch I suppose. I had simply looked at getting to LEO altitude, but staying there once you let go of the cable is a whole different ball game. I believe the only way to get into orbit from a space elevator (lacking additional power) is to go right to geostationary height? Let go anywhere under that altitude and you go into orbital decay.

Out of interest, where did you get the 1MJ/kg and 30MJ/kg values? As far as power stations, the new generation twin reactor {{w|Hinkley Point C nuclear power station}} (only know that one because its local to me) is designed to output 3.2GW, so 2.5GW isn't over the top. I would say that 240kW for aback yard solar farm is pretty large, depending on your location and size of back yard. --[[User:Pudder|Pudder]] ([[User talk:Pudder|talk]]) 17:11, 18 December 2014 (UTC)

I filled out the remaining fields. I thought about getting the interior capacities of all 1981 Oldsmobile models but doesn't seem worth it. It's clearly a joke so that kind of research doesn't seem necessary.

'''Arrow of Time'''
Did anyone else notice the special advert for Xmas gifts? It was up at the top of the main xkcd page yesterday 2014-December-17, but gone today (the 18th). In black, blue and red colored printing it said:
----
"The XKCD store Christmas shipping deadline is Friday!
Once it passes, there is no going back. The arrow of time drags us all
inexorably forward toward decay and disorder toward the end of all things.
Toward the empty silence of the grave. ORDER NOW!"
----
I thought it was amusing and saved a bitmap. Was kind of surprised that there was no other mention of this here, or on the fora either.

1461: Payloads

2014-12-17T19:44:50Z

108.162.216.171: Changed description of bottom panel from "the amount of mass they [various spacecraft] can deliver" to "the amount of mass which various rockets can deliver"

{{comic
| number = 1461
| date = December 17, 2014
| title = Payloads
| image = payloads.png
| titletext = With a space elevator, a backyard full of solar panels could launch about 500 horses per year, and a large power plant could launch 10 horses per minute.
}}

A larger version of the image can be found [http://imgs.xkcd.com/comics/payloads_large.png here].

==Explanation==
{{incomplete|Discuss space elevator aspect from title text, touch on horsepower vs [[rocket equation]], thrust, specific impulse, payload to orbit. E.g., compare with question of a horse getting itself into orbit?}}
This comic lists the payload capacity of several launch vehicles, and the mass of several spacecraft, in number of horses. This could be related to Randall's hobby of abusing dimensional analysis, as horses/ship is technically a perfectly acceptable derived unit, provided the size of a horse is standard (in this comic it appears that 'one horse' is defined as 450 kg). In cases where the mass is less than one horse, an alternative measure of dogs has been used, where one dog appears to be roughly 40 kg. In the case of {{w|Vanguard 1}}, even a dog is too large a measure, so instead the unit squirrel is used to represent its 1.47 kg mass.

The overall comic is an allusion to {{w|horsepower}}, a similar-sounding but completely different concept. Horsepower is a measurement of {{w|power (physics)|power}} ({{w|work (physics)|work}} per unit time). Another commonly referenced unit for power is the {{w|watt}}. 1 horsepower is meant to be approximately the amount of power a horse can deliver. In contrast, Randall uses the horse to measure {{w|mass}} (of spacecraft themselves, and of the payload they carry).

The top pane of the comic shows the mass of various spacecraft, while the bottom shows the amount of mass which various rockets can deliver to {{w|low earth orbit}}. There are also several joke insertions. In the top, one is T-Rex. In the bottom, another is Pegasus (the payload capacity given as one Pegasus); this is a reference to both Pegasus {{w|Pegasus (rocket)|the rocket}} and Pegasus the {{w|Pegasus|mythical flying stallion}}. Atlas-Centaur is also measured in centaurs, a reference to the half-human half-horse creatures of Greek mythology. The bottom also gives the 1981 {{w|Oldsmobile}} as 4 horses; this references the carrying capacity (by weight) of the Oldsmobile, not the ability of an Oldsmobile to launch that payload into low earth orbit.

The Pegasus, 1981 Oldsmobile, and Stratolaunch spacecraft are depicted horizontally, presumably because these vehicles launch from a horizontal starting position and use forward momentum to facilitate their launch.

There is an unlabeled launch vehicle below the H-11A near 2002. The unlabeled vehicle has a playload mass of 21 horses (9450 kg).

===Tables===
The tables below contain data relating to each entry on the comic image.

*Name - Should be as shown in the comic
*Launch Date - Date of first flight
*Mass/Payload (Horses) - Value as given in comic
*Mass/Payload (kg) - Independently researched value

{|
|- style="vertical-align:top;"
|

{| class="wikitable sortable"
!colspan="4"|Spacecraft Mass
|-
!Spacecraft
!Launch Date ''{{w|ISO 8601}}''
!Mass (Horses)
!Mass (kg)
|-
|{{w|Sputnik 1|Sputnik}}
|1957-10-04
|2 Dogs
|83.6
|-
|{{w|Vanguard 1}}
|1958-03-17
|Squirrel
|1.47
|-
|{{w|Pioneer 5}}
|1960-03-11
|Large Dog
|43
|-
|{{w|Venera 1}}
|1961-02-12
|1
|643.5
|-
|{{w|Mariner 2}}
|1962-08-27
|3 Dogs
|202.8
|-
|Apollo
|
|67
|
|-
|{{w|Venera 7}}
|1970-08-17
|3
|1,180
|-
|{{w|Pioneer 10}}
|1972-03-03
|7 Dogs
|258.8
|-
|{{w|Skylab}}
|1973-05-14
|171
|77,088
|-
|{{w|Venera 9}}
|1975-06-08
|11
|4,936
|-
|{{w|Voyager 2}}
|1977-08-20
|2
|721.9
|-
|Shuttle (Total)
|
|206
|
|-
|Shuttle (Payload)
|
|54
|
|-
|{{w|Mir}}
|1986-02-20
|288
|129,700
|-
|T-Rex
|
|15
|6,800
|-
|{{w|Hubble}}
|1990-04-24
|25
|11,110
|-
|{{w|Compton Gamma Ray Observatory}}
|1991-04-05
|38
|17,000
|-
|{{w|Corona (Satellite)|Keyhole 3}}
|
|40
|
|-
|{{w|International Space Station}}
|1998
|932
|450,000
|-
|{{w|Cassini-Huygens|Cassini}}
|1997-10-15
|11
|5,300
|-
|{{w|Huygens (spacecraft)|Huygens Lander}}
|1997-10-15
|1
|319
|-
|{{w|Rosetta (spacecraft)|Rosetta}}
|2004-03-02
|6
|2,900
|-
|{{w|Opportunity (rover)|Opportunity}}
|2003-07-07
|5 Dogs
|185
|-
|{{w|Dawn (spacecraft)|Dawn}}
|2007-09-27
|3
|1,240
|-
|{{w|TerreStar-1|Terrastar}}*
|2009-07-01
|15
|6,910
|-
|{{w|Dragon (spacecraft)|Dragon}}
|2010-12-08
|17
|
|-
|{{w|Tiangong-1}}
|2011-09-29
|19
|8,506
|-
|{{w|Curiosity (rover)|Curiosity}}
|2011-11-26
|2
|900
|-
|{{w|Corona (Satellite)|Keyhole 7}}
|
|40
|
|-
|{{w|Orion (spacecraft)|Orion (Capsule)}}
|2014-12-05
|20
|8,913
|-
|{{w|James Webb Space Telescope|James Webb Telescope}}
|
|14
|6,200
|-
|{{w|Orion (spacecraft)|Orion}}
|2014-12-05
|20
|8,913
|-
|{{w|Orion Service Module}}
|
|25
|12,000
|-
|{{w|Deep Space Habitat|Orion Deep Space Habitat}}
|
|65
|
|}

Terrastar is believed to be a mis-spelling of {{w|TerreStar-1|TerreStar}}, based on its mass and launch date.

|

{| class="wikitable sortable"
!colspan="4"|Lauch Vehicle Capacity
|-
!Spacecraft
!Launch Date ''{{w|ISO 8601}}''
!Payload (Horses)
!Payload (kg)
|-
|{{w|Sputnik (rocket)|Sputnik Launcher}}
|1957-10-04
|1
|500
|-
|{{w|Thor-Able|Thor}}
|1958-04-24
|3 Dogs
|120
|-
|{{w|Mercury-Atlas}}
|1960-07-29
|3
|1,360
|-
|{{w|Saturn I}}
|1961-10-27
|20
|9,070
|-
|{{w|Proton-K}}
|1967-03-10
|44
|
|-
|{{w|Atlas-Centaur}}
|1962-05-08
|8 Centaurs
|
|-
|{{w|Titan IIIA}}
|1964-09-01
|7
|3,100
|-
|{{w|Saturn IB}}
|1966-02-26
|45
|21,000
|-
|{{w|Soyuz (rocket)|Soyuz}}
|1966-11-28
|14
|6,450
|-
|{{w|Saturn V}}
|1967-11-09
|262
|118,000
|-
|{{w|Black Arrow}}
|1969-06-27
|4 Dogs
|135
|-
|{{w|N1 (rocket)|N1}}
|1969-02-21
|211
|90,000*
|-
|{{w|Long March 1}}
|1969-11-16
|2
|300*
|-
|{{w|N-I (rocket)|N-I}}
|1975-09-09
|4
|1,200*
|-
|{{w|Delta 0100|Delta 0900}}
|1972-07-23
|3
|1,300
|-
|{{w|Ariane 1}}
|1979-12-24
|3
|1,400
|-
|{{w|Satellite Launch Vehicle|SLV}}
|1979-08-10
|1 Dog
|40
|-
|{{w|N-II (rocket)|N-II}}
|1981-02-11
|4
|2,000
|-
|{{w|Oldsmobile#1970s-1980s|1981 Oldsmobile}}
|1981
|4
|
|-
|{{w|ASLV}}
|1987-03-24
|4 Dogs
|150
|-
|{{w|Long March 4A}}
|1988-09-06
|9
|4,000
|-
|{{w|Ariane 4}}
|1988-06-15
|16
|5,000-7,600*
|-
|{{w|Shavit}}
|1988-09-19
|6 Dogs
|350-800*
|-
|{{w|Energia}}
|1987-05-15
|218
|100,000*
|-
|{{w|Pegasus (rocket)|Pegasus}}
|1990-04-05
|1 Pegasus
|443
|-
|{{w|Atlas I}}
|
|13
|
|-
|{{w|PSLV}}
|
|8
|
|-
|{{w|J-I}}
|
|2
|
|-
|{{w|Long March 3B}}
|
|27
|
|-
|{{w|H-IIA}}
|
|22
|
|-
|(unlabelled) {{w|Delta IV#Delta IV Medium|Delta IV M}}?
|
|21
|
|-
|{{w|Delta IV Heavy|Delta IV-H}}
|
|64
|
|-
|{{w|Falcon 1}}
|
|1
|
|-
|{{w|Ariane 5#Variants|Ariane 5ES}}
|
|47
|
|-
|{{w|H-IIB}}
|
|37
|
|-
|{{w|UNHA}}
|
|2 Dogs
|
|-
|{{w|Atlas V|Atlas V 541}}
|
|38
|
|-
|{{w|Falcon 9}}
|
|29
|
|-
|{{w|Antares (rocket)|Antares}}
|
|14
|
|-
|{{w|Stratolaunch}}
|
|14
|
|-
|{{w|Falcon Heavy}}
|
|118
|
|-
|{{w|Space Launch System|SLS Block 1}}
|
|156
|
|-
|{{w|Space Launch System|SLS Block 1B}}
|
|217
|
|-
|{{w|Space Launch System|SLS Block 2}}
|
|289
|
|}

|}

==Transcript==
{{incomplete transcript}}

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Animals]]
[[Category:Space]]

Talk:521: 2008 Christmas Special

2014-11-08T18:31:55Z

108.162.216.171:

Santa actually really is Muslim. Saint Nicholas was from Turkey, although his remains have been somewhere in Italy for the past millennium.{{unsigned ip|121.222.232.156}}
: Yeah, right. Living in what was later to be Turkey makes him a muslim. Islam was not even invented yet. [[User:Undee|Undee]] ([[User talk:Undee|talk]]) 11:44, 5 November 2013 (UTC)
Of course you have to explain how St Nick who died in 343 CE could have been following a religion whose founder was born in 570 CE. But you knew that. I also think we can do somewhat better than "somewhere in Italy". His tomb is at Basilica di San Nicola in Bari, Italy. {{unsigned ip|108.162.237.11}}

And also, equating Santa with St Nicholas is problematic at best. Santa came about as an amalgamation of many different figures from folklore, so even if St Nick were Muslim, at best you could call Santa part-Muslim.[[Special:Contributions/108.162.216.171|108.162.216.171]] 18:31, 8 November 2014 (UTC)

I always thought Black Hat was talking to Danish. The hair's longer and it makes a modicum more sense that way (at least to me) Anonymous 03:34, 4 December 2013 (UTC) {{unsigned ip|173.245.54.91}}
:I see what you are saying (although I couldn't comment on whether the hair is longer) but the question sounds like something Megan would ask. Danish would have built the laser chainsaw. [[Special:Contributions/108.162.219.223|108.162.219.223]] 19:20, 10 January 2014 (UTC)
::True... Anonymous 20:14, 13 February 2014 (UTC)
:I don't see Black Hat in any of the panels... [[Special:Contributions/173.245.55.83|173.245.55.83]] 14:50, 22 May 2014 (UTC)
::He is at the bottom line, first panel from left. --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 20:48, 23 May 2014 (UTC)

Just checked this image for any data in the black frames (like in [[SOPA]]). There is nothing; all pixels read #000000. [[Special:Contributions/108.162.216.53|108.162.216.53]] 20:52, 5 March 2014 (UTC)

I'm don't think "sublimate" means vaporize... And neither would vaporize fit with the rest the story... [[Special:Contributions/141.101.89.208|141.101.89.208]] 14:08, 14 May 2014 (UTC)

Sublimation is a specific type of vaporization. I don't think the exact nature of the board's destruction is important to the comic.[[Special:Contributions/108.162.216.171|108.162.216.171]] 18:31, 8 November 2014 (UTC)

Of all the black panels, i'm most curious about the contents of number 32. It would have made more sense if panel 31 read something like "From all of us to all of you, we wish you..."[[User:Mumiemonstret|Mumiemonstret]] ([[User talk:Mumiemonstret|talk]]) 09:37, 12 August 2014 (UTC)

Clones (cloned raptors) vs droids (cyborgs), and then victorious clones turning against their masters... Well, this raptors seem to be more independent then altered clones of Jango Fett but may be lightsabers aren't the only SW quote here.
[[Special:Contributions/141.101.92.202|141.101.92.202]] 16:53, 24 October 2014 (UTC)

520: Cuttlefish

2014-11-08T18:16:37Z

108.162.216.171: /* Explanation */

{{comic
| number = 520
| date = December 22, 2008
| title = Cuttlefish
| image = cuttlefish.png
| titletext = Unless the CS students finish the robot revolution before you finish the cephalopod one.
}}

==Explanation==
It appears that [[Cueball]] and [[Megan]] are physicists visiting a biology lab. Their guide gives them a description of the humble {{w|cuttlefish}} that is both accurate and makes them sound like other-worldly creatures with highly advanced capabilities.

The scene takes an unusual turn when the scientist implies that the cuttlefish have been easily trained to improve its capabilities. He then demonstrates this by giving a simple command, whereupon the cuttlefish attack and kill both Cueball and Megan, demonstrating an ability to fly, talk and discharge lethal electric shocks.

This is all revealed to be a dream, but it has given Cueball a warning not to underestimate the biologists. Apparently, they can be just as crazy and dangerous as any other kind of scientist. Cueball offers a toast to all biologists everywhere and plans an alliance with them against the chemists, hoping to prevent further attacks on physicists. The scientists are shown drinking from laboratory flasks, stereotypical behavior for biologists (and chemists).

In the past, [[Randall]] has been somewhat dismissive of the non-math / non-physics scientific disciplines, so this comic may be trying to mend some bridges with biologists. But not with chemists.

In the title text, CS stands for Computer Science. The "robot revolution" references events in film and literature, wherein robots, having become commonplace in the workforce, achieve independent thought and declare war on humanity (One example being the Terminator). Randall implies that the physicists will switch sides if the robot revolution arrives first. Cephalopod means a squid-like or octopus-like creature

==Transcript==
:We visit a bio lab: [Cueball and Megan visit a bio lab where they look into a tank that the scientists point at.]
:Scientist: These are cuttlefish.

:[Image of a cuttlefish.]
:Scientist: They're frighteningly smart, have manipulating arms and tentacles, have ink jets, can dart backwards and see the polarization of light through their w-shaped pupils. And their sides are 200 dpi display screens which they use for camouflage and communication.

:Scientist: When we realized how intelligent they were, we began to teach them. They've advanced quickly. Cuttlefish: GO.

:[Cuttlefish float out of the tank at Cueball and Megan.]

:Cuttlefishes: Kill the physicists... kill the physicists

:[Cuttlefish zap Cueball and Megan as they fall.]

:[Cueball waking up from his sleep.]
:Cueball: Oh god. I knew it.

:XKCD{{sic}}
:Salutes Bio Majors
:[Bottle is pouring into a flask, and a man takes the flask and drinks from it.]
:If we join you against the chemists, will you train your fleshy minions to leave us alive?

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Chemistry]]
[[Category:Biology]]

1433: Lightsaber

2014-10-13T14:32:33Z

108.162.216.171: Edited Vader's lines in transcript to be bold and italic, matching the comic (and convention from comic 1397)

{{comic
| number = 1433
| date = October 13, 2014
| title = Lightsaber
| image = lightsaber.png
| titletext = A long time in the future, in a galaxy far, far, away, astronomers in the year 2008 sight an unusual gamma-ray burst originating from somewhere far across the universe.
}}

==Explanation==

This comic references a [http://www.youtube.com/watch?v=WDnoczxzQyg scene] from the third theatrically-released ''{{w|Star Wars}}'' movie, ''[[wikia:c:starwars:Return of the Jedi|Return of the Jedi]]'', wherein [[wikia:c:starwars:Darth Vader|Darth Vader]] confronts his son, [[wikia:c:starwars:Luke skywalker|Luke Skywalker]], who had recently surrendered to [[wikia:c:starwars:Galactic Empire|Imperial]] soldiers. In the movie Vader notes that Luke Skywalker has constructed [[wikia:c:starwars:Luke Skywalker's lightsaber|a new lightsaber]] following the loss of his [[wikia:c:starwars:Luke skywalker#Lightsabers|original]] during their [[wikia:c:starwars:Duel on Cloud City|duel on Cloud City]] (Luke Skywalker's original lightsaber actually having been Anakin Skywalker's second). It makes a joke on the fact that a real laser would not have any way of stopping, and would therefore continue forever. Because Vader slightly tilts the active lightsaber, the beam ends up slicing straight through the hull of a large section of the Death Star. Randall maybe also makes a reference to "Hull Breach", a science fiction space combat playing card game.

The title text makes allusion to {{w|GRB_080319B|GRB 080319B}}, an unusual gamma ray burst in 2008, visible to the human eye - if the lightsaber continued forever, it could theoretically have been the cause of GRB 080319B. The {{w|Star_Wars_(film)|Star Wars}} {{w|Star_Wars_opening_crawl|opening crawl}} starts with the text "A long time ago in a galaxy far, far away...", so emitted light could end up in our time when traveling a long distance.

Luke Skywalker and Darth Vader have had a similar conversation before in [[1397: Luke]].

==Transcript==
:[Luke Skywalker and Darth Vader are talking. Vader holds the handle of a powered-off lightsaber.]
:Vader: '''I see you have constructed a new lightsaber.'''
:[Vader turns it on. The beam of the lightsaber continues upward out of the frame.]
:Lightsaber: Snap-Hisss
:[Vader looks up toward where the beam is pointing.]
:[Vader looks back at Luke.]
:Vader: '''Where does it end?'''
:Luke: Doesn't.
:Intercom (out of view): ''Hull breach all along sector five!!''
{{comic discussion}}

1433: Lightsaber

2014-10-13T04:23:56Z

108.162.216.171:

Talk:929: Speculation

2014-10-11T04:27:16Z

108.162.216.171: response to last comment

I love the comics like this that work on multiple levels. They really lend to the legitimacy of xkcd as a thinking man's webcomic, and they're great comics to link to when I'm trying to make a point. '''[[User:Davidy22|{{Color|purple|David}}y²²]]'''[[User talk:Davidy22|<tt>[talk]</tt>]] 09:24, 9 March 2013 (UTC)

It's a bolt. Longbows fire arrows, crossbows fire bolts. 'K?
:That bolt looks maighte like an arrow to me... but let's not quarrel about this. --[[User:Qwach|Qwach]] ([[User talk:Qwach|talk]]) 23:35, 31 August 2013 (UTC)
::Crossbows do fire bolts, so the only reason you wouldn't want to quarrel about it is because you would be wrong.
::However, the word "arrow" comes from the official transcript, so YOU don't want to quarrel about it either, 'K? [[Special:Contributions/108.162.219.223|108.162.219.223]] 07:19, 21 January 2014 (UTC)

::Quarrel? [http://en.wikipedia.org/wiki/Quarrel]--[[Special:Contributions/141.101.99.9|141.101.99.9]] 12:57, 18 March 2014 (UTC)
::: Please check your adds on the preview before committing it here. Everything you do save here is viewable to everyone; that's just annoying. I just want to see your primary intention, because THAT'S IMPORTANT, if that doesn't work fix it at PREVIEW before we get a mess here. I'm just happy if I can understand what you are talking about. --[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 00:27, 19 March 2014 (UTC)

The explanation states that it is Black Hat speaking in the title text. It makes much more sense if it is Randall speaking, but just demonstrating a slightly black-hat tendency. In my opinion. [[Special:Contributions/108.162.219.223|108.162.219.223]] 17:58, 21 January 2014 (UTC)
:Yeah, but in the original comic's title text, it uses the single-quotes--that wasn't just added by explainxkcd as a formatting thing. When Randall is supposed to be the one speaking, there are no quotation marks in the title text... that implies this one is a quote from Black Hat. [[Special:Contributions/108.162.216.171|108.162.216.171]] 04:27, 11 October 2014 (UTC)