1. Class 3 : Craters in the solar system. Recap last class… Patterns in the solar system. Theory for solar system formation. How do we test this theory? Variety of surfaces in the solar system Classifying surfaces. The processes at work.

2. I : Classification of surfaces Can classify surfaces in the Solar System into the following groups: Heavily cratered. Mildly cratered. Blotchy/linear features. Shrouded by an atmosphere. Processes that are relevant: Impacts by asteroids, comets etc. Volcanic activity. Atmospheric erosion. Let’s look at this in some more detail.

3. II : Heavily cratered bodies Far side of The Moon

4. Two kinds of terrain: highlands and maria

6. The Moon & Mercury Very little or no atmosphere… All incoming meteors hit the surface (different from Earth where small objects burn or break up). Once made, craters stay (any erosion processes happen very very slowly). Located in the inner solar system More rocky (outer moons are icy), so craters survive longer. More debris to cause craters.

7. Lunar Terrain Highlands Several kilometers higher. Heavily cratered. 4 – 4.4 billion years old. Aluminum rich rock (light colored). Maria (“seas”) Younger (3.2 – 3.9 billion years old). Iron rich rock (dark color). Old Lava flows (like Hawaii on Earth today).

9. Another sign of lava flows… lunar rilles are believed to be remains of old lava flows.

11. III : Volcanism in the solar system Io – the most active volcanic region in the Solar System

12. Examples… Io Very smooth surface – no craters or rilles. Thought to be a very young surface – lava has filled all craters and valleys. Strong stretching/pulling by Jupiter heats interior and causes volcanic activity. Mars Possesses some giant dead volcanoes (e.g. Olympus Mons… 27km high, 600km wide). Example of a crater not caused by impacts.

14. IV : The outer moons – ice geology at work. Europa

15. Surface ice sheet occasionally seems to break and float around on an underlying liquid water ocean