The observed properties of the Solar system. Have the primitive features been removed by recent activity. Be able to recognize which planet is which by its appearance. Mass determined from Kepler's laws of planet has a moon or change in orbit of passing space probe.
Magnetic fields provide evidence of metallic conducting cores.
Outer Skins of Planets and Moons Know what factors modify the surfaces of planets or Moons. Know which processes are important on what major objects in the solar system. Planetary Atmospheres Actual atmospheric composition of the atmospheres of the major planets, especially Venus, Earth, Mars and the outer gas-ball planets. The absence of an atmosphere on the Moon and Mercury. Origin and change of planetary atmospheres.