1. Terrestrial Planets

3. Sources of internal heat

5. Planetary Interiors ► If everything else were equal  The internal heat is proportional to the volume of the planet, which goes as the cube of the radius  The rate of heat loss depends upon the area of the surface, which goes as the square of the radius

6. Net result ► The ratio of stored heat versus cooling goes something like R, the radius ► Thus, all else being equal, we expect the interior of a larger planet to be warmer than the interior of a smaller planet

7. Differentiated Interiors

10. Volcanism Mars Olympus Mons

11. Volcanism Venus

12. Volcanism Earth

13. Plate Tectonics

14. Venus, tectonics yes, but not plate tectonics

15. Mars: activity mostly in the past?

16. Valles Marineris

18. Moon: Geologically dead?

19. Mercury ► Similar to the Moon, but with small lava plains rather than the giant maria

20. Mercury: Cliffs created by crustal movement ► Did Mercury shrink as it cooled?