Comment this is weak (Score 1) 233
Have we detected the impactor, on the earth or on the moon? If we haven't then it is eminently plausible that the impactor had the same composition as the earth/moon. Or is there a way to suppose that after this collision, all of the mass of the impactor remained separate from the thing it impacted, which became the earth and the moon? Maybe we got hit by dark matter? I think the conclusions are running way ahead of the facts here.