This is one of those comics that's set up like it's a parody of something, but it doesn't make sense that that something would be parodied. I mean, a good comedian can make humor out of anything, and you can get all postmodern and mess with formula and expectations. It just seems to me that Manhattanhenge is a weird thing to poke fun at.
The last two panels also feel weirdly disconnected from each other. The both follow from the original panel, but in different ways. I know he was going for a double punchline, but it seems jumpy I think it'd be better if there was a clearer transition between them, like "Oh yeah, well what's that?" and then the that would be the sun.
The sun gag is a really lame joke, but that's obvious. It kinda reminds me of a school of comedy writing that I'm given to understand exists in anime: A random thing happens and some guy says "This doesn't make any sense!". (I don't watch anime, this is based off of something my friend Lachlan told me once) And while I don't think Randy's graduated from that same school, I think he's done at least a semester there if you catch my drift.