They think no one actually knows the only reason that moon is there, is because it originated form a moon god cult. (religion.blogs.cnn.com)
Although the two teams worked unaware of each other, they reached the same conclusion: A large impact can indeed form both moons. (sciencemag.org)
This Giant Impact Hypothesis suggests that the outer layers of Earth and the object were flung into space and eventually formed the moon. (sciencedaily.com)