Dina, who was fifteen, and Ivo, who was fourteen, were in the school science club with five other children and their teacher, Ms. Okonkwo. Their big project was a balloon. They filled it with helium and tied a foam box to it, and inside the box were a small camera, a phone for tracking and a parachute, packed so carefully that Ivo had checked it nine times.
On Saturday at nine o'clock the club stood on the school field and counted down. "Three, two, one!" The balloon rose into the clouds until it was only a dot, and then it was gone. An hour later the phone lost its signal. About thirty kilometers up, the balloon burst, as planned, and the parachute brought the box back down, somewhere.
The children climbed into Ms. Okonkwo's old van. The last signal said "east of the river". They searched for hours: roads, fields, a wet ditch that took Ivo's shoe. At four in the afternoon the phone beeped once. In a cabbage field an old farmer, Mrs. Dolan, sat on a bucket next to the white box. "Is this yours?" she asked. "My cow tried to eat the parachute."
At school they opened the camera. The photos showed the field getting smaller, then clouds, then a sky as dark as night at midday, with a thin blue curve: the edge of the Earth. Nobody spoke. The last photo was a huge, blurry cow's nose. Everyone laughed, and the club hung the two photos side by side: "The Edge of the Sky" and "The Edge of the Cow".
