explain xkcd - User contributions [en]

2062: Barnard's Star

2019-12-10T14:59:32Z

Nerd Sniper: /* Explanation */

{{comic
| number = 2062
| date = October 22, 2018
| title = Barnard's Star
| image = barnards_star.png
| titletext = "Ok, team. We have a little under 10,000 years before closest approach to figure out how to destroy Barnard's Star." "Why, does it pose a threat to the Solar System?" "No. It's just an asshole."
}}

==Explanation==
[[File:Near-stars-past-future-en.svg|thumb|300px|Distances to the nearest stars from 20,000 years ago until 80,000 years in the future]]
{{w|Barnard's Star}} is a very-low-mass {{w|Red dwarf|red dwarf}} about 6 light-years away from Earth in the constellation of {{w|Ophiuchus}}. It is the fourth-nearest known individual star to the {{w|Sun}} after the three components of the Alpha Centauri system; it is the closest star to Earth in the Northern Hemisphere. It is a red dwarf with a mass of 0.144 Solar masses, a diameter one fifth that of the Sun, and it is 7–12 billion years old. Because of this low mass the gravitational pressure in the core is much lower and thus the fusion rate is far smaller than in the core of the Sun. In fact this star is so dim that, even though it's one of the nearest, it can't be seen by the naked eye. The low fusion rate also means that the lifespan of small stars is much longer. While huge stars might last a few hundred million years, and the Sun about 10 billion years, a small red dwarf has a lifespan of about a trillion years.

Barnard's Star is the star with the greatest proper motion in the sky. Proper motion is motion in the sky other than that caused by Earth's rotation or orbit.Barnard's star is both very close to the sun (as these things go) and moving now at a speed of more than 140 km/s toward the Sun. It will make its closest approach to the Sun in approximately 10,000 years, at a distance of about 3.75 light-years.

The image on the right shows different stars near the Sun over 100,000 years and it can be seen that none of them are getting closer than 3 light-years. This is a safe distance to our Solar System and the stars will not influence the orbits of the planets or smaller bodies. It's also obvious that much closer approaches never have happened since the Solar System formed 4.5 billion years ago because otherwise the nearly circular orbits of the planets in the same plane wouldn't be possible. Closer encounters have happened in the past by mostly small stars like {{w|Scholz's Star}} which actually passed through the {{w|Oort cloud}} at a distance of 0.82 light-years about 70,000 years ago, and at least one estimate suggests that a star is expected to pass through the Oort Cloud every 100,000 years or so. This distance is still too far away to influence the orbits of the planets, but those encounters cause {{w|Comet|comets}} perturbed from the Oort cloud to the inner Solar System roughly 2 million years later.

The comic shows the sizes and the distances not in a proper scale. If the Sun was 1.4 cm (1.4 Mio km in real) in diameter, Barnard's Star would be less than 3 mm at a distance of 356 km. Even Jupiter wouldn't fit into this picture -- at ten times smaller than the Sun, it would be a few pixels, but at a distance of 7.8 m to the Sun and all the other planets would fit into a circle less than 100 meters in diameter. The distances to others stars are far beyond human imagination and at its closest distance a message still takes 3.75 years from Barnard's Star to the Sun.

In regards to "20,000-year-long high-speed flyby", the joke here is suggesting Barnard's Star would need to scream out the maleficent, trolling statement as quickly as possible due to 20,000 years being such a small segment of time relative to the lifespan of the star (and our Sun, for that matter).

The title text emphasizes that this close approach will not be any hazard to the Solar System, but someone is envious of the long lifetime of Barnard's Star or annoyed by its unpleasant behavior (yelling at the sun for 20,000 years would be a minuscule amount of time for the stars, but for humans it would be a vast length of time, and would get annoying very quickly).

==Transcript==
:[A black sky is shown with a yellow spot near the bottom, left of the center. Three smaller red spots at the diagonal from top left to bottom right indicate a moving star over time. Above these red spots lines are connected to a text that starts and ends with many ''A''s, first growing, and at the end getting smaller:]
:...AAAAHHi Sun! I was here billions of years before you formed and will shine for trillions of years after you dieEEEEEEAAA...

:[Caption below the frame:]
:Sometimes, I wonder what Barnard's Star is saying to the Sun as it performs its 20,000-year-long high-speed flyby.

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Comics with inverted brightness]]
[[Category:Astronomy]]

2239: Data Error

2019-12-10T14:55:10Z

Nerd Sniper: /* Explanation */

{{comic
| number = 2239
| date = December 9, 2019
| title = Data Error
| image = data_error.png
| titletext = Cyanobacteria wiped out nearly all life on Earth once before, and they can do it again!
}}

==Explanation==
{{incomplete|Created by some <s>anomolous</s> ''perfectly normal'' algae. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
[[Megan]] is frustrated that a data error invalidates her research, which was ready for publication. [[Black Hat]] suggests two options: redo her analysis and share the correct results, trying to extract some value from the research; or, as our classic [[classhole]] says, she should destroy the evidence, build a superweapon and dominate the world. She seems excited about this idea, and proclaims that people should fear her algae, which would probably be her superweapon, but then she remembers that her first research was incorrect because of the data error, so they are merely normal algae.

In fact, destroying the evidence, hiding the error and publishing the wrong results as if they were right is what a dishonest scientist would do in such a situation. This is what a lot of readers would expect a dishonest character as Black Hat to suggest in panels two and three. However, the unexpected turn in mid of last panel changes leaves {{w|scientific misconduct}} to go to pure supervillain.

The title text refers to the {{w|Great Oxidation Event}}, when prokaryotic photosynthetic organisms built up oxygen in Earth's atmosphere for the first time and most organisms, which weren't adapted to oxygen, went extinct. That suggests that algae may be somehow dangerous - although {{w|cyanobacteria}}, which are colloquially referred to as "blue-green algae", are not considered to be true algae by many scientists, who restrict the term to eukaryotes.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[Black Hat and Megan stand facing each other.]
:Megan: I can't believe this data error invalidates a year and a half of my research.
:Megan: I was about to publish.

[:Black Hat and Megan stand facing each other. Black Hat has his hands raised slightly]
:Black Hat: Don't panic. You have two options.
:Megan: Yeah?

:[Closeup shot of Black Hat holding one hand up.]
:Black Hat: 1) Redo your analysis and share whatever results you can, whether positive or negative. It's disappointing, but these things happen.

:[Zoom out on Black Hat and Megan. Black Hat has closed his fist. Megan holds her arms up in the air.]
:Black Hat: 2) Destroy the evidence. Use your materials and research methods to build a superweapon. Conquer Earth and rule with an iron fist.
:Megan: '''''Tremble before my anomalously productive algae!'''''
:Megan: Except the anomaly was an artifact.
:Megan: '''''Tremble before my normal algae!'''''

{{comic discussion}}
[[Category:Comics featuring Black Hat]]
[[Category:Comics featuring Megan]]
[[Category:Biology]]
[[Category:Science]]

Talk:434: xkcd Goes to the Airport

2019-12-09T15:24:05Z

Nerd Sniper:

I do not understand the "churchmouse" in this context? This needs an explain. Thanks.--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 20:39, 26 August 2013 (UTC)
:A churchmouse is a small rodent. Look it up on Wikipedia. '''[[User:Davidy22|{{Color|#707|David}}y²²]]'''[[User talk:Davidy22|<tt>[talk]</tt>]] 02:23, 27 August 2013 (UTC)
::That's not true: http://dictionary.reference.com/browse/church+mouse [[User:Xhfz|Xhfz]] ([[User talk:Xhfz|talk]]) 23:24, 13 October 2013 (UTC)
::Alice in Wonderland creates the door mouse. A church mouse is either ameek but faithful church-goer or referencing the idiom "poor as a church mouse." Either way, I don't get it, either, Dgbrt.07:42, 18 December 2014 (UTC)Nix
:::There are no church mice in Alice in Wonderland. There is a [https://en.wikipedia.org/wiki/The_Dormouse dormouse] but that's a real animal. I'll update the text. [[User:Jkshapiro|Jkshapiro]] ([[User talk:Jkshapiro|talk]]) 14:20, 7 July 2016 (UTC)
:Later, [[526 | Converting to Metric]] informs us that a fieldmouse contains 3 mL of blood.--[[User:Rael|Rael]] ([[User talk:Rael|talk]]) 05:29, 6 September 2013 (UTC)
::According to my calculations, it's closer to 1.5 mL/0.05 oz. This is based on a house mouse with 80 ml/kg of blood. {{unsigned ip|108.162.237.192}}

Maybe I'm just dirty minded, but I thought the "stains panties" line had to do with simulating either defloration or menstruation.--[[Special:Contributions/67.243.62.50|67.243.62.50]] 17:16, 28 September 2013 (UTC)
:I believe it's a reference to the "underwear bomber" who brought a liquid explosive onto a plane by sneaking it in his underwear
[[Special:Contributions/108.162.218.179|108.162.218.179]] 04:23, 19 July 2016 (UTC)
I was under the impression that the "hacker girl" either gave him the set as a gift, or he just learned how to lock-pick from being around her so much that he acquired his own. It seems weird that it would have anything to do with smuggling. [[Special:Contributions/76.106.251.87|76.106.251.87]] 01:12, 22 October 2013 (UTC)

Am I the only one who thought the second panel was a reference to '147: A Way So Familiar'? Mostly based on the character's enthusiastic obsession with a girl who is probably a very bad influence, or at least a bad match. - Pennpenn [[Special:Contributions/108.162.249.205|108.162.249.205]] 05:44, 14 January 2015 (UTC)

They tell you to turn the devices off because the airplane travels very quickly. The devices will try and connect to the towers on the ground, but it will have to change towers. This messes up the network (hundreds of phones connecting and disconnecting). [[Special:Contributions/199.27.133.76|199.27.133.76]] 00:22, 11 September 2015 (UTC)
:Given the altitude would most phones even be in range to attempt to connect? Anyway, I was always under the impression it was to prevent to off-chance of the transmissions from messing with the plane's systems. -Pennpenn [[Special:Contributions/108.162.250.162|108.162.250.162]] 05:16, 20 November 2015 (UTC)

Interestingly enough, google searches for "blood in a churchmouse" spiked the day this comic went up.
http://www.google.com/trends/explore#q=blood%20in%20a%20churchmouse {{unsigned ip|108.162.220.17}}

"Much fewer blood"? And it was required for electronics to be turned off long before portable phones became ubiquitous, so it's not ''only'' the cell connections freaking the network out. --[[Special:Contributions/108.162.237.226|108.162.237.226]] 02:16, 17 January 2017 (UTC)

Lockpicks aren't actually illegal though. I have a set myself.