I could swear that I've read a comic with almost the exact structure, setup, etc, as the first comic, but I can't remember anything about it so I can't prove that Randy's treading old ground. JUST TRUST ME OKAY??
I've mocked XKCD for trying too hard to be 'relatable' before (and I will again, just try and stop me!) but I think this is definitely worse. These seem like anti jokes, jokes that you'd have a character say and the joke is that he's trying and failing to be funny.
Dara O Briain has a bit at the beginning of one of his stand up specials where he talks about how sometimes he gets shit for not making jokes about Muslims even though he makes jokes about Catholics and etc. And he says, do you know what he says, I'll tell you what he says: "1. I don't know a thing about Muslims. 2. Neither do you." (watch the special, his delivery is what makes that joke) Later in either that special or the next one, he does a bit about that movie 2012, and he goes and explains the rough plot as the first part of the bit.
It's such a simple solution. Your audience needs to know something to understand a joke you're going to make? Exposit knowledge at them in the form of more jokes. Randy is just assuming we know what the heck he's talking about.
I will say that I do like the idea of a constellation called "Rexthor, The Dog-Bearer", though. Also it was nice of Randy to make a joke about graphs instead of making a joke in the form of a graph.