Research suggests that the earth and moon may have formed as a result of a collision between the earth and another object, possibly a neighboring planet or close neighbor. The details of this event are still being studied, with some simulations indicating it may have occurred quickly, while others propose the moon formed within a vaporized earth synestia. The earth and moon's compositions may not be as similar as previously thought, with new analysis of apollo samples revealing exotic sulfur in the moon's mantle.