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		<id>https://www.explainxkcd.com/wiki/index.php?title=1677:_Contrails&amp;diff=119397</id>
		<title>1677: Contrails</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=1677:_Contrails&amp;diff=119397"/>
				<updated>2016-05-06T18:16:33Z</updated>
		
		<summary type="html">&lt;p&gt;Donjohnson: /* Explanation */&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{comic&lt;br /&gt;
| number    = 1677&lt;br /&gt;
| date      = May 6, 2016&lt;br /&gt;
| title     = Contrails&lt;br /&gt;
| image     = contrails.png&lt;br /&gt;
| titletext = Astronomy (or &amp;quot;astrology&amp;quot; in British English) is the study of ...&lt;br /&gt;
}}&lt;br /&gt;
&lt;br /&gt;
==Explanation==&lt;br /&gt;
{{w|Contrail}}s (short for &amp;quot;condensation trails&amp;quot;) are trails of vapor produced by aircraft exhaust, trailing the airplane.  They are formed from water condensing on jet fuel exhaust particles, some impurities of which provide bases for ice crystals to accumulate on. Some can dissipate in minutes, but others can last for hours or even longer, depending on the temperature and wind conditions at that particular altitude.  The {{w|chemtrail conspiracy theory}} claims that contrails lasting unusually long are actually chemical or biological agents sprayed into the air for sinister purposes. There is no evidence such a thing is happening.&lt;br /&gt;
&lt;br /&gt;
Here, [[White Hat]], presumably speaking with a British accent, notices that there are a lot of contrails in the air. [[Cueball]] corrects him, saying that in {{w|American English}}, contrails are called chemtrails, which is, of course, incorrect.&lt;br /&gt;
&lt;br /&gt;
This is another comic in the [[:Category:My Hobby|My Hobby]] series. Many of these comics involve [[Cueball]] giving misleading information about pedantic terms, such as [[1405: Meteor]]. Another [[966:_Jet_Fuel]] mentions chemtrails as being &amp;quot;full of [] mind-control agents&amp;quot;.&lt;br /&gt;
&lt;br /&gt;
The title text implies that {{w|astronomy}} and {{w|astrology}} are synonymous, with astrology being the term used in British English. However, this is incorrect. Though both involve studying celestial objects, astrology is the pseudoscience that interprets positions of celestial objects as having influence on human affairs, while astronomy is the scientific study of celestial objects on a universal scale.&lt;br /&gt;
&lt;br /&gt;
The joke is that British English and American English often call the same object with different terms, and one can often learn new words for a simple thing. This, however is not the case in this comic; contrail and chemtrail do not refer to the same thing, the latter being only a subtype of the former. And it being xkcd, we can assume that chemtrail is a term that is frowned upon. Thus the comic states it as misinformation.&lt;br /&gt;
&lt;br /&gt;
The title text includes a similar situation: astronomy is the scientific study of things in outer space, like stars, planets, and galaxies. Astrology, however, is a system that infers one’s personalities and characteristics from zodiacs of her date of birth, which is a constellation assigned to a period of time in a year. The same system can also derive predictions about future, especially that of a relationship. Some would argue that astrology shows statistical values, but it is hardly science by the standards of scientific study.&lt;br /&gt;
&lt;br /&gt;
Given that the &amp;quot;American English&amp;quot; version is the conspiracy theory one for contrails/chemtrails, while who confuses astronomy and astrology is not fully clear, it is possible that the rest of the explanation of the astronomy vs astrology text would describe astrology. In that case, this could be a comment on the educational status in the US vs the UK, where conspiracy theories and superstition (astrology) are much more prominent in the US than in the UK (or Europe in general).&lt;br /&gt;
&lt;br /&gt;
==Transcript==&lt;br /&gt;
:[Cueball and a White Hat are walking. White Hat is looking up to the sky while Cueball, walking in front holds out one arm towards him.]&lt;br /&gt;
:White Hat: Lots of contrails today.&lt;br /&gt;
:Cueball: Oh, you must be from the UK. In American English it's &amp;quot;Chemtrail&amp;quot;.&lt;br /&gt;
&lt;br /&gt;
:[Caption under the panel]&lt;br /&gt;
:My hobby: Spreading linguistic misinformation&lt;br /&gt;
&lt;br /&gt;
{{comic discussion}}&lt;br /&gt;
&lt;br /&gt;
[[Category:Comics featuring White Hat]]&lt;br /&gt;
[[Category:Comics featuring Cueball]]&lt;br /&gt;
[[Category:My Hobby]]&lt;br /&gt;
[[Category:Language]]&lt;/div&gt;</summary>
		<author><name>Donjohnson</name></author>	</entry>

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