The so-called "Ninnion Tablet" is a votive red-figured attic clay plaque, found in the Sanctuary of Eleusis and dated ca. 370 BCE. It is a private offering, not of the utmost artistic quality, with an original subject of mortals encountering the Eleusinian deities. The complex iconography has been extensively discussed in classical scholarship. A frieze depicting a series of lunar discs and crescents, which has not been given much attention yet, crowns the main scene. In the present paper, we examine these moons and conclude that they may be the oldest representation of the phenomenon of earthshine in western art.