The cover for "Celestial Wonders" should feature a stunning depiction of a vibrant nebula, with swirling colors of purple, blue, and gold. In the foreground, a silhouette of a spaceship or an astronaut gazes out at the expansive universe, which is filled with sparkling stars and distant galaxies. The title "Celestial Wonders" should be integrated into the design, enhancing the overall theme of exploration and cosmic beauty.