1. Slide 1 Observations/Inferences: Rocky inner, icy outer solar system Asteroid differentiation temperatures heliocentrically distributed Gross zonal structure within asteroid belt preserved The Moon had a magma ocean The solar photosphere has a composition very similar to CI carbonaceous chondrites Heat source concentrated near Sun? or Longer times to accrete object farther from the sun (less Al heating)? 26

2. Slide 2 Heat Sources: Solar/Magnetic Induction heating (but T-Tauri: Polar Flows) Short-lived radioisotopes ( 26 Al 0.73 Ma half life: must accrete fast) Long-lived radioisotopes (U, Th, K) (slow, only for larger bodies) Large impacts (only for larger bodies: between Moon and Mars-sized) Potential energy of core formation (larger bodies: 6300 km radius: 2300°C rise, Resonant tidal heating (Only moons: Moon?, Titan, Io, Europa) 3000 km radius: 600°C rise)

3. Slide 3 Timing of Core formation

4. Slide 4 Two Possible Mechanisms to Separate Metal from Silicate Porous FlowImmiscible Liquids and Deformation

5. Slide 5 Dihedral (wetting) Angle Theory The Dihedral Angle Theta is a force balance between interfacial energies

6. Slide 6 Sulfide Melt in an Olivine Matrix Most Fe-Ni-S melts do not form interconnected melt channels

7. Slide 7 0 Depth km Pressure GPa 500 750 250 15 22.5 0 7.5 Pressure GPa after Carlson, 1994 No Crystal Settling Perovskite Settling Low Mg/Si Dunite High Mg/Si Liquid 15 22.5 0 7.5 Crystal Cummulates t Quench Crust Quench Crust Magma Ocean Crystallization Cummulates should give a chemical signature

8. Slide 8 Lower Mantle Solidus d u s ( u p p e r b o u n d ) CoreT Multianvil Peridotite Solidus Olivine shock melting M a g n e s i o w ü s t i t e m e l t i n g Zerr et al (98), Holland & Ahrens (97) Diamond Anvil Peridotite Solidus

9. Slide 9 Earth Structure

10. Slide 10 Ray Paths

11. Slide 11 D’’ Heterogeneity

12. Slide 12 Great Earthquakes

13. Slide 13 Samples Recording Planetary Differentiation

14. Slide 14 Pallasites: Asteroid Core-Mantle Boundary Brenham

15. Slide 15 Old Lunar Highland Crust

16. Slide 16 An Oblique Collision between the proto- Earth and a Mars-sized impactor 4.2 minutes 8.4 minutes12.5 minutes Kipp and Melosh (86), Tonks and Melosh (93)

17. Slide 17 Temp

18. Slide 18 Temp

19. Slide 19 Temp