How are solar systems born? Many of us remember those school-room models of our Solar System, with tiny wooden planets rotating at the ends of their wires around a bright-orange painted sun. But how accurate is the model? Do the planets really align in a plane, or do their orbits crisscross around the sun at different angles? It turns out the toy isn’t too far off, at least in this one aspect. Our solar system is actually pretty flat, with most of its planets orbiting within three degrees of the plane of the Earth’s orbit around the sun, called the ecliptic. This flatness extends to the asteroid belt between Mars and Jupiter, though some members of the region of icy objects past Neptune called the Kuiper belt are more extreme, with inclinations up to 30 degrees.