Are all of the inner planets similar? Why not?

• Although the inner planets are roughly similar to each other, and the outer planets are similar to each other, there are some important differences, especially, for example, if one wanted to consider a visit to other planets. The details of the nature of each planet is different. Also, planets are not totally uniform (they're not the same in the center as on the outside), and they change as time passes. So we can talk about the evolution of planets, we will discuss physical processes that are important on each planet.

• Terrestrial planets
  • Earth has water on its surface. It is partially covered by clouds

  • Venus is covered by clouds all of the time. However, we can probe the surface using radar mapping and find that there is topography: rolling plains, highlands, and lowlands.

  • Mercury is mostlyl craters

  • Mars has some craters. It has polar caps and large-scale dust storms.

• Important physical processes on inner planets: plate tectonics, volcanism, eroseion, cratering
  • Relative importance of different processes depends largely on two things
    • Presence of atmosphere
    • Presence of internal heat

  • Both of these are related to mass of the planet: more massive planets generally retain more atmosphere and retain more internal heat.