Daddy was washing the jeep. Aura was lying in the grass, looking up. "Daddy. You said space is black." "It is!" Daddy said. He kept scrubbing. Aura pointed straight up at the sky. "Then why is the sky blue?" Daddy stopped scrubbing. "...Oh," he said. He put down the sponge and sat in the grass next to her. He picked up the hose and put his thumb over the end so the water came out in a fine mist. The sun caught the mist, and a tiny rainbow appeared in it. "Look," Daddy said. "Sunlight looks white. But it is really every color mixed together. The rainbow just pulls the colors apart so you can see them." Aura looked at the little rainbow. "Our air is full of tiny bits," Daddy said. "Way too small to see. When sunlight comes down through them, those bits bounce the blue light around more than the other colors. The blue gets knocked all over the sky. So everywhere you look, blue is coming back at you." "So the blue is... the air?" Aura said. "Right," said Daddy. "The sky isn't blue. Our air is." Aura lay back in the grass and thought about that. "So the sky is actually black," she said. "We're just looking through blue." Daddy lay down beside her in the wet grass. "...Yes," he said. The jeep stayed half washed. The hose kept running. Neither of them got up for a while. If you went up and up, past the clouds, past the airplanes, past the very last of the air, the blue would run out. There would be nothing left up there to bounce it around. That is where the black starts. The black was there the whole time. Our air was just standing in front of it. Look up tomorrow. You are not looking at blue. You are looking through it.