From “Moon formation: Was it a ‘hit and run’ accident?” (BBC News, July 27, 2012), we learn,
In a report online to be published in Icarus, researchers suggest that the crash happened with a much larger, faster body than previously thought.
Such theories need to line up with what we know about the Moon, about the violent processes that set off the creation of moons, and what computer simulations show about the more sedate gravitational “gathering-up” that finishes the job.
In recent years, scientists’ best guess for how the Moon formed has been that a relatively slowly moving, Mars-sized body called Theia crashed into the very young Earth.
Sounds good, but …
While the Moon has an iron core like Earth, it does not have the same fraction of iron – and computer models supporting the Theia impact idea show just the same thing.
The nice thing about science news is that it is not the summer reruns. There really can be new ideas.