explain xkcd - User contributions [en]

1551: Pluto

2015-07-15T08:06:47Z

108.162.250.169: /* Table of objects */ Extended 'cracks' and 'predator attack' sections

{{comic
| number = 1551
| date = July 14, 2015
| title = Pluto
| image = pluto.png
| titletext = After decades of increasingly confused arguing, Pluto is reclassified as a "dwarf Pluto."
}}

When the image is clicked the latest [http://www.nasa.gov/feature/new-horizons-spacecraft-displays-pluto-s-big-heart-0 NASA post] opens up.
==Explanation==
{{incomplete|New Page.}}

This comic was posted on Tuesday, July 14th 2015, in honor of the {{w|New Horizons}} deep space probe making its flyby at {{w|Pluto}}. It thus breaks the regular Monday/Wednesday/Friday cycle for the [[xkcd]] comics. [[Randall]] has taken the largest released image by this day and drawn humorous {{w|Pareidolia|pareidolia}} on top of it.

It can be compared to preliminary descriptions by geologists, e.g. [http://www.planetary.org/blogs/emily-lakdawalla/2015/07140911-new-horizons-best-look-at.html?referrer=http://t.co/ExQJ6cKS1Q New Horizons' best look at Pluto before close approach | The Planetary Society].

===Table of objects===
{| class="wikitable"
|-
! Description
! Explanation
|-
| Candy shell
| Suggests Pluto is a confection.
|-
| JPEG plumes
| The {{w|JPEG}} image format has the common issue of slightly distorting an image with {{w|Compression artifact}}s. The artifacts shown here do not appear in the official version of this image, and may have been added by [[Randall]] (or edited out by NASA). But there have been tweets about people seeing plumes associated with active volcanoes and the like, which were explained as being artifacts.
|-
| Frontal bone
| Interpreting Pluto as a head, the {{w|frontal bone}} could be the light-colored region next to the darker top (the north pole).
|-
| Grease stains
| The darkened area of Pluto's north pole is attributed to grease.
|-
| Bugs
| Could refer to possible extraterrestrial life on Pluto in to form of {{w|insects}}, or "bugs". (In the animated TV series ''Roughnecks: Starship Troopers Chronicles'', an adaptation of Robert Heinlein's novel ''Starship Troopers'', the first battles with the alien "Bugs" took place on Pluto.)
|-
| Bullet holes
| A string of small round features which Randall suggests were the result of Pluto getting shot repeatedly.
|-
| New Netherlands
| Reference to [[1519: Venus]] and also a [[what if?]] about draining the Earth's oceans onto Mars. In that What If?, the Netherlands issued forth from the portal that drained the oceans to claim Mars as New Netherlands. Presumably something similar happened on Pluto.
|-
| Disputed territory
| Since the base photograph is identified as "today's ''New Horizons'' image," this indicates that a section of Pluto has immediately become the subject of some controversy, possibly a territorial claim or one of several references to the fact that Pluto was demoted from full planet status in 2006.
|-
| Snake pit
| A generic map hazard.
|-
| Full text of the Wikipedia article on pareidolia
| {{w|Pareidolia}} is the human brain's tendency to see patterns where they don't exist. While probably a reference to the famed {{w|Face on Mars}}, the joke is also recursive: You'd be seeing the text of a Wikipedia article explaining to you that you couldn't actually be seeing the text of a Wikipedia article.
|-
| Tadpole
| One of a number of pareidolic features Randall has outlined.
|-
| Kuiper Belt loops
| The {{w|Kuiper belt}} is a region in our solar system that contains a large concentration of icy bodies, including Pluto. Randall jokingly refers to Kuiper Belt as the same kind of belt that's used to fasten clothing, and identifies features on Pluto's surface as loops for the belt.
|-
| Serenity
| An outline of the ''Firefly''-class spaceship ''Serenity'', which was the titular vessel from the 2002 TV series ''{{w|Firefly}}''. One of a number of pareidolic features Randall has outlined.
|-
| Dinosaur
| One of a number of pareidolic features Randall has outlined.
|-
| The good part
| A random, arbitrary selection of Pluto that is somehow better than the rest of Pluto.
|-
| Moon bud
| This could be interpreted as a moon growing/emerging out of pluto, as a bud is "a compact knob-like growth". A round growth is seen at the location marked, resembling a small, emerging moon.
|-
| Ghost
| A reference to the classic video game ''{{w|Pacman}}'', wherein the primary antagonists are one of four Ghosts. The Ghost on Pluto appears to have a mouth, however, unlike most depictions of the ''Pacman'' Ghosts. One of a number of pareidolic features Randall has outlined.
|-
| Pluto dinosaur extinction crater
| Suggests Pluto had dinosaurs and lost them the same way Earth did.
|-
| Heart
| One of a number of pareidolic features Randall has outlined, and the only one (currently) also informally named as such by NASA.
|-
| Coronary artery disease
| Also known as {{w|ischemic heart disease}}, which causes degradation of heart tissue. The region identified in the comic looks less 'healthy' (is darker and more ragged) compared to the rest of the 'Heart', which Randall suggests is caused by the disease.
|-
| Mount Mons
| Referring to the general practice of naming extraterrestrial mountains {{w|Mons (planetary nomenclature)|"X Mons"}} (e.g. {{w|Olympus Mons}}, a mountain on Mars and the largest mountain in the Solar System), as well as naming terrestrial mountains "Mount X". Since "mons" is Latin for "mountain", the feature's suggested name translates as "Mount Mountain".
|-
| Charging socket
| A terrain feature suitable for connecting an outside source of electricity for the benefit of implied internal batteries. Compare "dock connector," below.
|-
| Cracks (beginning to hatch)
| Implying that Pluto is some manner of giant egg. Possibly a reference to the ''Doctor Who'' episode ''Kill the Moon'', in which the Moon is revealed to be an egg from which a monster is hatching. An 2014 article from ''The Onion'', [http://www.theonion.com/article/moon-finally-hatches-36414 "Moon Finally Hatches,"] makes the same joke. Also possibly a reference to ''The Light Fantastic'', a ''Discworld'' novel in which similar objects are revealed to be the eggs of the world turtle.
|-
| Scars from predator attacks
| Since it's all-caps, we can't tell if "PREDATOR" is a proper noun, but this is possibly a reference to the movie series ''{{w|Predator (franchise)|Predator}}'', about a race of aliens who hunt other beings for sport. Alternatively, a planetary predator may have previously scarred Pluto.
|-
| Reset button
| The structure indicated is a small black dot (at least at this distance this picture was taken). Reset buttons on home electronics are often small buttons or holes used to reset the software of the electronic device.
|-
| Debate Hole

Where we're putting all the people still arguing about Pluto's planet status
| Pluto was reclassified as a {{w|dwarf planet}} rather than a {{w|planet}} following the latter term's controversial {{w|redefinition in 2006}} by the {{w|International Astronomical Union}}. Arguments about the classification continue to pop up. The same argument is referenced in the title text.
|-
| Area missed during ironing
| The area indicated is near the {{w|Terminator (solar)|terminator}} and shows some intriguing topographic relief.
|-
| Probably Benign
| A {{w|neoplasm}} or tumor is an abnormal growth of tissue. Randall is suggesting that the abnormal region near the heart has been evaluated by a doctor and determined to be {{w|Benign tumor|benign}}.
|-
| Chocolate frosting
| Suggests the discrepancy in color over Pluto's surface may be a function of what cake frosting was used where.
|-
| Vanilla frosting
| As above, suggests the discrepancy in color over Pluto's surface may be a function of what cake frosting was used where.
|-
| Border of pride lands
| A reference to the Disney animated feature ''The Lion King.'' In the movie, the Pridelands is the bright and prosperous region ruled by the Lion King while a dark territory beyond its border is controlled by hyenas. The border identified in the comic corresponds with a feature NASA calls the "whale's tale," with the rest of the whale being the large dark splotch.
|-
| Hyena country
| A continuation of the ''Lion King'' reference above.
|-
| Dock connector
| From the point of view of the photograph, this feature of Pluto is at the planet's "bottom," where iPod dock connectors are. Compare "charging socket," above.
|}

==Transcript==
:'''PLUTO'''
:Some of the features already identified in today's ''New Horizons'' image

:[Many marks on the image of Pluto follow:]

:Candy shell
:Frontal bone
:Grease stains
:Bugs
:JPEG plumes
:Full text of the wikipedia article on pareidolia
:Bullet holes
:New Netherlands
:Disputed territory
:Snake pit
:Tadpole
:Pluto dinosaur extinction crater
:Kuiper beltloops
:Serenity
:Ghost
:Dinosaur
:The good part
:Moon bud
:Scars from predator attacks
:Reset button
:Megaman
:Charging socket
:Cracks (beginning to hatch)
:Plug (inflating/deflating)
:HEART
::Mount Mons
::Coronary artery disease
:Debate hole
::Where we're putting all the people still arguing about Pluto's planet status
:Chocolate frosting
:Probably benign
:Vanilla frosting
:Dock connector
:Border of pride lands
:Hyena country
:Area missed during ironing

:Image credit: NASA/JHUAPL/SWRI - click for original

{{comic discussion}}
[[Category:Space]]
[[Category:Astronomy]]

Talk:1514: PermaCal

2015-04-21T12:49:54Z

108.162.250.169:

In Megan's response, the "h" in "19th" is backwards.
[[Special:Contributions/108.162.214.239|108.162.214.239]] 05:47, 20 April 2015 (UTC)
:I'm pretty sure that's a mistake since lowercase letters normally aren't used. [[User:Mikemk|Mikemk]] ([[User talk:Mikemk|talk]]) 05:49, 20 April 2015 (UTC)
:Looks like he forgot the line on the upper left. He used the capital 19TH for Cueball. [[Special:Contributions/173.245.48.60|173.245.48.60]] 07:24, 20 April 2015 (UTC)
:I think it's intentional. All the H's after a T have shortened upperleft lines. Probably for nice http://www.explainxkcd.com/wiki/index.php/kerning [[User:ToaVin|ToaVin]] ([[User talk:ToaVin|talk]]) 10:12, 20 April 2015 (UTC)
::I recall other examples where Randall's lettering style includes 'stroke obscurations' (preferable to merging of letters, probably).[[Special:Contributions/141.101.98.160|141.101.98.160]] 16:10, 20 April 2015 (UTC)

Leap seconds have nothing to do with the length of the year: corrected. [[Special:Contributions/108.162.249.162|108.162.249.162]] 07:49, 20 April 2015 (UTC)

"Leap seconds normally account for the differences in the length of our 24 hour day and the time taken for the world to rotate 360 degrees on its axis" - this sentence mixes two unrelated concepts. First, a day is not a rotation of 360 degrees. Because the Earth also orbit the sun, the rotation from noon one day to noon the following day is a bit more than 360 degrees (360.9856 or so) (rotation measured relative to the stars) - this is why constellations appear to move throughout the year. Second, leap seconds are required because the leap day corrections of the Gregorian calendar are good, but not perfect, at matching the difference between Earth orbits (years) and Earth rotations (days). Every so often, a small correction is required. The corrections are not regular because the causes of the drift are numerous: tidal effects, orbital eccentricity, the underlying (small) flaws in the calendar, etc. I have not made any changes in the explanation. --[[Special:Contributions/141.101.104.66|141.101.104.66]] 08:41, 20 April 2015 (UTC)

Not unrelated concept. Just not fully understood. Rotate 360 degrees is a simple way of putting things that ignores the diffrence between solar days and sidereal days. Incorrect not because someone doesn't understand the topic being discussed but because someone hasn't studied astronomy or seriously thought about how the movement of the Earth effects the length of the day--[[Special:Contributions/108.162.237.183|108.162.237.183]] 13:00, 20 April 2015 (UTC).
:Guilty. No excuse either, because I actually knew (but just forgot) about the difference between sidereal and solar days. [[Special:Contributions/108.162.249.162|108.162.249.162]] 01:14, 21 April 2015 (UTC)

While you are true on one part, that Earth doesn't take 24 hours to rotate 360 degrees (it takes around 23 hours and 56 minutes if I recall correctly), leap seconds are used to account for differences between 24 hours and a solar day. If it was used to adjust the length of the year the time of day would drift, it would also be fairly pointless as the leap days take us out by 1/4 of a day.[[Special:Contributions/108.162.250.175|108.162.250.175]] 10:41, 20 April 2015 (UTC)

Do we know for sure that this comic was released on a Sunday - the 19th instead of the 20th? The first entry in this page is from the 20th. Of course there are some references to the 19th, but then again it is obvious that it is on the 20th that Megan asks. Anyone who can find out if this is the correct date, or just a mistake by someone who misunderstood something based on the dates in the comic? --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 11:19, 20 April 2015 (UTC)
:Yes, it was released on the 19th, at about 10 PM CST. All of the recent comics have been released a few hours early though, so if you want the date set at 20, fine. [[User:Mikemk|Mikemk]] ([[User talk:Mikemk|talk]]) 15:05, 20 April 2015 (UTC)
:The archive claims that it was released on the 20th.--[[User:17jiangz1|17jiangz1]] ([[User talk:17jiangz1|talk]]) 15:08, 20 April 2015 (UTC)
Apropos a "permanent calendar", Isaac Asimov proposed just such a calendar. http://calendars.wikia.com/wiki/World_Season_Calendar This web page unfortunately doesn't go into details, but there were several advantages. The same calendar is used for all years, your birthday is always on the same day of the week, no need to remember "30 days hath Sept. ...", and several other advantages I can't remember right now. --[[User:RenniePet|RenniePet]] ([[User talk:RenniePet|talk]]) 12:45, 20 April 2015 (UTC)

There is some confusion between the different types of astronomical time: a day in mean solar time is 24 hours, with a difference of + or - up to 1 second (compared to time on an atomic clock), in apparent solar time is 24 hours + or - up to 30 seconds, and in mean sidereal time is 23 hours, 56 minutes, 4.0916 seconds (according to Wikipedia), and there is one extra sidereal day (about 366.25) in a sidereal year. [[User:The Dining Logician|The Dining Logician]] ([[User talk:The Dining Logician|talk]]) 13:55, 20 April 2015 (UTC)

It seems like our collective favorite word just might be "portmanteau" [[User:YourLifeisaLie|The Goyim speaks]] ([[User talk:YourLifeisaLie|talk]]) 13:42, 20 April 2015 (UTC)

The explanation seems unclear where it addresses the title text. I'm not sure what is meant by "maybe 100ms every few months," but it seems to miss the point of the comic. If a leap day is added each time the previous day ends, then at millisecond resolution, a new leap-millisecond would be added every millisecond! Hence the resulting DDOS when pushing so many NTP notifications... [[Special:Contributions/199.27.133.104|199.27.133.104]] 16:05, 20 April 2015 (UTC)
:I think that's wrong, too. Just my vote towards encouraging someone who wants to consider rewording it.[[Special:Contributions/141.101.98.160|141.101.98.160]] 16:10, 20 April 2015 (UTC)

I want to clarify a bit here. Leap days account for the fact that the rotation period of the Earth does not evenly divide into the revolution period. As such we can predict when each leap day will happen in the future. Leap seconds on the other hand are due to variance in the Earths rotation caused by various factors. Leap seconds cannot be predicted and must be observed by measurement and corrected for after the fact. It is based on the fact that the Earth's rotation varies.

I am so happy Randall decided to mock leap seconds. The human race just needs to accept that the rotation of the Earth is not a constant and stop pretending that it is. If we ingored leap seconds it would only add up to a few hours a lifetime. So what if 12pm is a different time as the years pass? It may be annoying but that is the world we live one. We can still have noon be the height of the sun if we want, it will just be a different time. [[Special:Contributions/199.27.133.73|199.27.133.73]] 17:25, 20 April 2015 (UTC)
:Does that last paragraph add anything to the article? The title text is mocking leap seconds about as much as the main comic is mocking leap days (ie- not really), and the odds that a server is able to handle NTP corrections due to regular clock drift, but unable to handle a 1 second jump in a single NTP correction seems like very poor mojo. I have no idea why the linux hrtimer subsystem cared about the wall-clock time, since it's a well known fact that the wall-clock time can change for a large number of reasons, and so you can't have your system go haywire every time it does. Google hasn't actually fixed anything, they are simply offering an NTP service that provides leap second corrections over a long smear - at the cost of being out of sync with UTC for up to a second at a time.
::If anything, that link to livescience needs to be removed as the worst kind of fear-mongering and click-bait. GPS doesn't care about leap seconds, and GPS time is well-known to drift from UTC; if your GPS receiver is making adjustments for leap seconds, then it's going to be inaccurate in every other way, as well.
::Also, given enough time, the day will be 25 hours long, for a few hours a week drift if you want to stick to UT as your arbitrary timekeeping system! [[Special:Contributions/108.162.249.162|108.162.249.162]] 01:32, 21 April 2015 (UTC)
::: I concur, the last sentence adds nothing to the explanation and should probably be removed. [[User:Spongebog|Spongebog]] ([[User talk:Spongebog|talk]]) 03:53, 21 April 2015 (UTC)

[[Special:Contributions/108.162.250.169|108.162.250.169]] 12:49, 21 April 2015 (UTC) An illustrative quote comes to mind: "By an equally suspicious freak of temporal relastatics, it is nearly always Saturday afternoon just before the bars close." Description of Ursa Minor Beta, The Restaurant At The End of The Universe, chapter 4.