A few people told me they didn't quite understand the point, or indeed the joke, in this one. (So no, it wasn't just you!) In order to try to rectify my inadequate plot explication, I made an alternate version, viz:

You may also note that in the original version (now removed) I referred to the forest moon as Endor. BobP, inveterate Star Wars geek, pointed out to me that the gas giant is named Endor, and the moon is not given a name. Although I argued that the line "the forest moon of Endor" is ambiguous, and could be interpreted along the lines of "the ice planet of Hoth" or "the swamp planet of Dagobah", BobP pointed out to me that those usages never occur in Star Wars. Additional canon reference material confirms that Endor is the name of the gas giant, not its moon.

So naturally I fixed this most egregious error. Irregular Webcomic! is nothing if not pedantically geeky.

BobP also suggested a simplified script for this strip, aimed at rectifying Vader's rather stultifying grasp of astrophysical jargon: