Explain xkcd: It's 'cause you're dumb.
Title text: So far Voyager 1 has 'left the Solar System' by passing through the termination shock three times, the heliopause twice, and once each through the heliosheath, heliosphere, heliodrome, auroral discontinuity, Heaviside layer, trans-Neptunian panic zone, magnetogap, US Census Bureau Solar System statistical boundary, Kuiper gauntlet, Oort void, and crystal sphere holding the fixed stars.
Voyager 1 is a U.S. space probe launched in 1977 to study the outer reaches of the Solar System and beyond. Popular press has on several occasions announced that it "has left the solar system" at each point when a boundary has been confirmed or a major event has taken place. This underscores the fact that there is no strictly defined and recognizable boundary of the solar system, or at least we haven't found one yet.
The title text lists several such possible boundaries, together with fictive humorous ones:
- The termination shock – the point in the heliosphere where the solar wind slows down to subsonic speed (relative to the star) because of interactions with the local interstellar medium.
- The Heliopause (astronomy) – the theoretical boundary where the Sun's solar wind is stopped by the interstellar medium.
- The heliosphere – a region of space dominated by Earth's Sun, a sort of bubble of charged particles in the space surrounding the Solar System.
- The heliosheath – the region of the heliosphere beyond the termination shock.
- Heliodrome – yet another composition of helios "sun," here together with dromos "course". There is no astronomical object with this name, but it has been used variously in other contexts. One that became famous is a sports hall which was used as a concentration camp in the Bosnian war, see Heliodrom camp.
- Auroral discontinuity - another fictitious astronomic object, for auroral see Aurora (astronomy).
- Heaviside layer – a layer of ionized gas occurring between roughly 90–150 km (56–93 mi) above the ground in the Earth's atmosphere. Popularly recognized for its use as a reference to Heaven in the writings of T. S. Eliot adapted into Andrew Lloyd Webber's musical Cats.
- Trans-Neptunian panic zone – this fictional zone combines the word from two subjects: "Trans–Neptunian" is used in astronomy to describe stuff that occurs beyond the planet Neptune. In Outdoor education the "panic zone" is the opposite of the comfort zone when trying to learn new stuff.
- Magnetogap – part of an ignition system.
- US Census Bureau Solar System statistical boundary – a fictive boundary defined by the United States Census Bureau, similarly to how it defines census areas for the purpose of processing statistical data about regions in the United States.
- Kuiper gauntlet – this is a play on the Kuiper belt, which is a region of the Solar System beyond the planets, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun, notable for being full of asteroids; replacing the word "belt" with "gauntlet (glove)" (often spelled 'gantlet') which is a protective glove as well as "gauntlet (punishment)" which is a medieval punishment where one would be forced to run through two lines of men who would hit the punishee.
- Oort void – refers to the Oort cloud, a gigantic "cloud" of materials (mainly composed of ice) which ends around a light-year from The Sun and is deemed the (current) "edge" of the solar system. The "void" may be pun on density of that "cloud" - the number of bodies in it may be huge, but given its size, it's mostly empty.
- Crystal sphere holding the fixed stars – this refers to historical ideas about the universe, particularly the Ptolemaic system, in which the stars were supposed to be fixed on a large crystal sphere around the Earth. It might also be referencing "The Crystal Spheres", a short story by David Brin, in which humanity's first interstellar ship shatters a previously undetected, protective barrier around the solar system. It may also be a reference to the Dungeons and Dragons setting "Spelljammer".
See also Voyager over the “heliocliff,” but Solar System transition mysterious article on Ars Technica.
- Number of times Voyager 1 has left the Solar System
- [22 tally marks.]
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Uh, not all tally marks are Doctor Who references. Alpha (talk) 05:49, 22 March 2013 (UTC)
Is it just me, or is Randall getting lazy? Most of the past comics have been simplistic, easy-to-draw charts. 184.108.40.206 (talk) (please sign your comments with ~~~~)
- Having just come from the future, we can now surmise that he was prepping for the epic, month-long-and-running sandcastle comic that started in the strip after this one. Echo Seven (talk) 03:59, 21 April 2013 (UTC)
Oh, was he talking about the glove? I though it was referring to "running the gauntlet" for some reason. --220.127.116.11 07:17, 22 March 2013 (UTC)
No, that's "running the gantlet." Two words which are often confused for each other. Plus you could run a gantlet of people whacking you with their gauntlets. 18.104.22.168 13:21, 22 March 2013 (UTC)
- "Running the gantlet" and "running the gauntlet" are both acceptable uses, since both gantlet and gauntlet can be used for the punishment (however, "dropping the gantlet" would be incorrect, since gantlet only refers to the punishment, while gauntlet can refer to both the punishment and the glove). 22.214.171.124 01:30, 23 March 2013 (UTC)
He almost certainly meant 'gantlet'; I think Randall just got the two words confused (it happens frequently. At this point, dictionary.com lists both spellings as synonymous.) The medieval punishment makes much more sense in context (ie: lots of things that could potentially hit Voyageur.)126.96.36.199 13:31, 22 March 2013 (UTC)
- Well, I saw a straight wordplay belt→glove there. --Mormegil (talk) 14:21, 22 March 2013 (UTC)
- Gauntlet and gantlet are both fitting and humorous in the context. Homophones are great. 188.8.131.52 17:41, 22 March 2013 (UTC)
There were several stories two days ago saying it had left, then a correction from NASA saying it didn't.
Bugefun (talk) 07:21, 22 March 2013 (UTC)
Is it just me or is it unclear why are there sixteen leaving events described in the title text but twenty-two tally marks on the comic? 184.108.40.206 07:39, 22 March 2013 (UTC)
I just keep hoping that my children will be interested in space. Too late for me, NASA wouldn't want me, but surely my genes are still ok, I hope. To follow voyager down the rabbit hole of our expectations, what else can father ever ask? 220.127.116.11 08:05, 22 March 2013 (UTC)
No it is not just you why there are 22 tick marks, and only 16 countable exits.18.104.22.168 12:03, 22 March 2013 (UTC)
The Crystal Sphere may refer to a David Brin story used to explain the fermi paradox of why we have had no alien contact: http://en.wikipedia.org/wiki/The_Crystal_Spheres Schmammel (talk) 14:37, 22 March 2013 (UTC)
- Crystal Sphere could also be a reference to the old Spelljammer D&D setting where systems/galaxies were contained in crystal spheres. 22.214.171.124
- Which in turn is a reference to (well, really, direct borrowing from) the Ptolemaic astronomical concept, so it still comes back to the same thing. 126.96.36.199 13:30, 28 March 2013 (UTC)
"US Census Bureau Solar System statistical boundary – a fictive boundary defined by": I'm capable of reading 'fictive' as 'conventional' in this sentence; as in "the real census bureau really invented it, like they really invented census areas". I would not have been confused by 'fictional', or by 'a boundary fictively invented', but I'm not sure that the second one is good English. I may have studied too much sociology. 188.8.131.52 07:38, 23 March 2013 (UTC)
"Magnetogap" is probably wordplay on http://en.wikipedia.org/wiki/Magnetopause 184.108.40.206 (talk) (please sign your comments with ~~~~)
Big news today (September 12, 2013), as Voyager 1 leaves the solar system. http://www.nytimes.com/2013/09/13/science/in-a-breathtaking-first-nasa-craft-exits-the-solar-system.html and http://www.bbc.co.uk/news/science-environment-24026153 Porkypine (talk) 19:47, 12 September 2013 (UTC)
- I have seen this statements at NASA too, but now it's just "Voyager Embarks on Journey Into Interstellar Space" and "NASA Spacecraft Embarks on Historic Journey Into Interstellar Space". So, this is just the next marker for this comic. Randall should do an update. There is simply NO defined border, it's just an other media hype. Look at nasawatch.com for the Randall like critical statements. Correct is: Voyager is leaving out solar system. But objects surrounding our sun, like Sedna are much farther outside. It's just a hype, this comic definitively needs an update by Randall.--Dgbrt (talk) 20:53, 12 September 2013 (UTC)