nag
Explanation
The Joke
This comic is a promotional/meta strip rather than a traditional joke comic. Zach Weinersmith uses the strip to promote his book A City on Mars (co-authored with his wife Kelly Weinersmith). The strip announces a Kickstarter campaign for the book.
The main visual shows an illustration of the solar system with the caption "Close Enough" — a joke about the accuracy of the diagram. The text explains that backers can get various rewards, including a model of the solar system showing Earth's orbit around the Sun and the planets' relative positions.
The final panel has Zach apologizing for being annoying with the self-promotion, promising he'll "be annoying again in the final day" since the solar system "will self-destruct in 24 hours" — a tongue-in-cheek joke about manufactured urgency in Kickstarter campaigns, framed as a cosmic deadline.
The Humor
The humor here is lighter and more self-aware than a typical SMBC strip. Zach acknowledges the inherent awkwardness of using his comic as an advertising platform and leans into it, calling himself annoying. The "Close Enough" label on the solar system diagram is a self-deprecating joke about scientific accuracy. The final gag about the solar system self-destructing plays on the common Kickstarter tactic of creating urgency ("Only 24 hours left!") by escalating it to absurd cosmic proportions.