Princeton University Astrophysical Sciences 2015 Spitzer Lecturer Seminar - ADDED

The most successful scenario of formation of the Moon is that of an impact between a Mars-size embryo known as Theia and the protoEarth, which led to the formation of a hot protolunar disk from which the Moon formed. This model can explain many of the features of the Earth-Moon system, most notably its angular momentum and the iron-poor character of the Moon. A consequence of this scenario is that most of the Moon should have been derived from the impactor rather than the protoEarth. If the impactor were distinct from the protoEarth, then one would expect the present Moon to be distinct from the Earth. I will present the work done in my laboratory on this issue, notably regarding the isotopic compositions refractory elements Ca and Ti. The conclusion is that the Earth and Moon are isotopically very similar, questioning existing models of the formation of the Moon.