It's been a while since I've reviewed a classic. And the comic requested by Anon 12:27 is even older than Xkcd itself (the first 50 or so comics were posted on forums before Randall moved them to their own site).
Comic title: Kepler
Alt text: Science joke. You should probably just move along.
Yes, it actually says that.
And I think this is indicative of an earlier, more self-conscious, Randall. He knew his jokes were esoteric and geeky. And he accepted that as one of his flaws. B for self-consciousness. Now that he is surrounded by his echo chamber of fans, he falsely recognises it as a strength. If you don't understand the joke, then you aren't a true fan.
I'm going to step forward and confess that I don't understand the joke here. I have been skim-reading the Wikipedia article on Johannes Kepler, and I still don't understand the joke. I did learn a few things about Kepler, such as the fact that he developed new theories on planetary motion, and developed a platonic solid model of the solar system. So that's neat, right? Xkcd has caused me to learn something.
Wrong! I should not have to do research to understand a punchline, ever. Now don't get me wrong. I am scientifically curious, and I subscribe to a lot of educational Youtube channels. But I enjoy that knowledge for its own sake, not because some self-important nerd-god told me to learn it.
Let's use an analogy here. If your parents punish you by forcing you to read a boring textbook, and that textbook ends up being quite interesting, then it is to the credit of the people who wrote that book. In this analogy, the textbook is Wikipedia, and Randall is my dad.
So the few facts I learned about Johannes Kepler are to the credit of the anonymous volunteers who write Wikipedia, not to the shmendrik who sent me there in the first place. I would give him a grade at this point for standalone value, but it's become a dead horse at this point, so I'll just give him U for Ungradable (the bottom mark in British exams).
Nevertheless, there seems to be a widely held opinion among webcomic fans:
The added bonus, for me, is that looking up new information like that is just as enjoyable as reading the strip itself.~ Aaron Diaz, author of Dresden Codak
Let me just say that I disagree. But what's the alternative you say? We only make lowest-common-denominator jokes about farts and reality television? No. I say the context of the joke should explain the idea of the thing it is about.
To difficult you say? Feh! Here is an example of an Xkcd that does it right. Yes, the 'sudo make me a sandwich' one. Who here can honestly say this one is difficult to understand? It is obvious from the context that sudo is a command that forces something to obey you, probably a piece of computer jargon that overrides all settings to give you admin permissions for that action. And the best part is that it was all conveyed in four lines of dialog. And I should point out that if you wanted to find out more about what sudo does, then you are free to do so.
I had to go to explainxkcd to find the actual meaning of comic 21, and it was a disappointment.
According to Kepler's Second Law, "A line joining a planet and the Sun sweeps out equal areas during equal intervals of time." This looks like wiping a wipe on the floor.
In the comic, the janitor Kepler also sweeps the same area, although in this case "area" is used in the sense of "surface" (of floor) rather than in the purely mathematical sense.
Really? It's not even the same meaning of the word area. Is that supposed to be a pun? Well it sucks. F for humour.
Also, why the fuck did he draw all these early Xkcds on squared paper? Did they not have plain paper at NASA? F- for lack of effort. See me after class.