Astro is a light aqua Toon with his face resembling a waning crescent moon. The right side of his face is pitch-black with a white star-shaped eye. He wears a cornflower blanket wrapped around his torso, obscuring his four arms to the point that they can be just seen as faint furrows in the blanket. However, his blanket is still short enough that it reveals his legs that are the same color as the crescent moon side of his face. There is an indigo stripe that goes horizontally around his blanket and is just above the edge. Underneath his blanket, he wears medium black shorts that are barely visible due to the blanket covering them, but previous versions of him never had the shorts. He wears a dangling sleeping cap the same color as the stripe on his blanket, with a light blue trim and a light blue pom-pom at the tip. During Blackouts, he emits a blue glow that changes color depending on the Skin equipped.