** CANCELLED ** Giant Impact Models of Lunar Origin

Duke Physics Colloquium
Robin Canup (SouthWest Research Institute)

*CANCELLED** "Giant Impact Models of Lunar Origin" - Nearly all recent work on lunar origin has focused on the giant impact theory, which proposes that the collision of a planet-sized body with the forming Earth produced a disk of debris that later accumulated into the Moon. The impact theory is strongly favored because it provides a natural explanation for the Moon's lack of a large iron core and the Earth's rapid initial rotation rate. However impacts capable of producing a lunar-sized Moon typically produce a disk of material derived from the impactor rather than from the Earth. This would most naturally produce a Moon whose composition differed from that of the Earth's mantle. Instead, the silicate Earth and the Moon are compositionally indistinguishable in multiple respects. I will describe current giant impact models, which are studied through 3D hydrodynamical simulations of planet-planet collisions. "Canonical" impacts involving a Mars-size impactor can explain the current angular momentum of the Earth-Moon system, but require post-impact mixing between the disk and the Earth to explain the similar compositions of the Earth and Moon. "High angular momentum" impacts can produce a disk with the same composition as the Earth's mantle, but require a gravitational resonance with the Sun to subsequently alter the spin rate of the Earth. Faculty Host: Horst Meyer. Dr. Canup will also give the Hertha Sponer Lecture on Thursday, February 20, sponsored by the President's Office

Wednesday, February 19, 2014 - 3:30pm
Physics 128
Paul, Cristin