1. Planetary Geology

6. Layering of Terrestrial Worlds The process of differentiation separates materials with different densities Dense metals fall to the central core Rocky material (minerals) form the mantle resting above the core The lowest density materials form the outer layers called the crust The crust and the outermost layers of the mantle form a rigid lithosphere (lower layers are softer)

7. Example of a Terrestrial World

8. Terrestrial Planets and the Moon The interiors are hotter and denser Note trends with size and distance from Sun

9. Three Sources of Internal Heating Accretion of planetesimals continues after formation and can change the composition slightly Differentiation occurs because the materials are hot and molten Nuclear reactions occur in the dense central regions

10. Planetary Cooling Conduction directly transfers heat from the lower layers to the upper layers Convection carries warmer parts of the mantle closer to crust Eruptions deposit hot lava onto the surface where it cools

11. Planetary Magnetic Fields Requirements for a planetary magnetic field: –Metal in liquid or molten form needed –Convection in these liquid layers –Moderately rapid rotation

12. Formation Properties and Controlling Factors

13. Geological Processes Impact cratering: asteroids, comets, and other planetesimals impacting the surface Volcanism: the eruption of molten rock (lava) onto the surface Tectonics: the disruption of the surface due to internal forces (e.g. convection in mantle) Erosion: the wearing down of surface features by water, wind, and other factors

14. Impact Cratering

15. The Moon Crater Tycho

16. Cratering on the Moon

17. Cratering Rate

18. Martian Crater

19. Volcanism

20. Volcanic Activity

21. The Near Side of the Moon

22. Tectonics on Earth and Venus

23. Past Tectonics on Mercury

24. One Type of Erosion: Wind