Explain SMBC — the wiki for Saturday Morning Breakfast Cereal

This is a promotional comic rather than a traditional joke strip. It announces the launch day for "A City on Mars," a book by Kelly and Zach Weinersmith (the SMBC creator and his wife). The comic-format announcement explains that the book took about four years of research and is about whether humans should settle space.

The text includes quotes from notable figures praising the book, including Andy Weir (New York Times bestselling author of "The Martian" and "Project Hail Mary"), Chad Orzel (New York Times bestselling author), Mary Roach (bestselling author of "Fuzz" and "Packing for Mars"), and James S.A. Corey (author of "The Expanse" series).

While not a joke comic per se, the humor is subtly present in the self-aware nature of using a webcomic to promote a book -- Weinersmith essentially breaking the fourth wall of his comic strip to do direct marketing. The Zach character ("ZACH!" appears as an enthusiastic header) is drawn in the typical SMBC style, blurring the line between the comic's fictional world and the real-world promotional purpose. This kind of meta-commercial content is a hallmark of SMBC, where Weinersmith regularly uses his strip to promote his books and projects while maintaining the comic's distinctive voice.