| Any theory of the origin of the solar system must be able to account for these properties of the planets. |
| Property 1: Sizes and compositions of terrestrial planets versus Jovian planets | The terrestrial planets, which are composed primarily of rocky substances, are relatively small, while the Jovian planets, which are composed primarily of hydrogen and helium, are relatively large (see Section 7-1 and Section 7-4). |
| Property 2: Directions and orientations of planetary orbits | All of the planets orbit the Sun in the same direction, and all of their orbits are in nearly the same plane (see Section 7-1). |
| Property 3: Sizes of terrestrial planet orbits versus Jovian planet orbits | The terrestrial planets orbit close to the Sun, while the Jovian planets orbit far from the Sun orbits versus Jovian planet orbits (see Section 7-1). |