"Seth on the Moon" is a bonus novella in the Zodiac Academy series by Caroline Peckham and Susanne Valenti, (#5.6 in the series) that details Seth's birthday trip to the moon gifted by his friend Caleb. It serves as an online chapter to celebrate the series' end and is a lighthearted addition, focusing on Seth's experience of his dream trip and his complicated feelings for Caleb. While it was initially released as a standalone online chapter, readers can also find it within the book Live and Let Lionel.