From time to time articles like this appear in the Washington Post or the New York Times with casually definitive statements like this:
Earth, along with the other planets in our solar system, formed about 4.5 billion years ago from a cloud of dust and gas swirling around the embryonic sun. For hundreds of millions of years, ours was a harsh, molten world, heavily bombarded by debris. At one point, a Mars-sized object slammed into the Earth and blasted into space the material that eventually cohered into the moon.
…as if none of it could possibly be questioned.