1. www.psrd.hawaii.edu/April07/irons.html When Worlds Really Did Collide Iron meteorite cooling rates –Compositional zoning –Size of intergrowths Intergrowths in taenite “cloudy zone” Zoning in taenite

2. www.psrd.hawaii.edu/April07/irons.html When Worlds Really Did Collide Cooling rates of group IVA irons (fourth largest group) range over a factor of almost 100 Implies cooling of a metallic core with little or no rocky insulation How do we produce a huge (300 km) blob of molten metal?

3. www.psrd.hawaii.edu/April07/irons.html When Worlds Really Did Collide Collisions of molten planetesimals may be the answer Consistent with dynamical models of planetary accretion