Today's comic is pure Gary Larson, who admittedly has influenced my style and sense of comedy a lot. It's not just that I like expressing the whole thing in a single panel, but the idea of finding something that genuinely puzzles you and then imagining a humorous theory, that would explain the situation. It's actually fun to see what kind of style this comic will have. I have no idea, this is the first time I'm doing this.
As for the actual answer for the question in the strip, we turn to Wikipedia: History of rockets.