By David Coppedge

Apollo ended 40 years ago, Neil Armstrong is dead; but lunar geologists are still using the moon rocks they brought home to construct a story of the moon’s “evolution”.

Hit and Run

Science news outlets went “luney” (luna=moon) this week with stories of a new impact hypothesis.  If you thought the impact hypothesis was old news, it’s back.    Wasn’t it solved years ago with the proposal that a Mars-sized object (it even had a name: “Theia”) hit the Earth to form the Moon?  Well, yes and no.  In August, PhysOrg revisited the “Lunar Paradox”—

Over the past decades scientists have simulated this process and reproduced many of the properties of the Earth-Moon system; however, these simulations have also given rise to a problem known as the Lunar Paradox: the Moon appears to be made up of material that would not be expected if the current collision theory is correct.…

If current theories are to be believed, analyses of the various simulations of the Earth-Theia collision predict that the Moon is mostly made up of material from Theia. However, studying materials from both Earth and the Moon, shows remarkable similarities. In fact, elements found on the Moon show identical isotopic properties to those found on Earth.

That’s too improbable–for an interloper to be that similar.  What to do?  Idea: envision a faster “hit-and-run” collision that lets Theia’s matter escape, but lets the debris reassemble into the Earth and Moon.  Problem solved?  Not yet; the author of a paper in Icarus hopes that additional computer simulations ” may finally lead to the long-searched solution of the lunar paradox,” i.e., one that can be “believed”….

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