Highest-resolution analysis of the Moon's impact-origin model

[SparWeb]

This is a big step up from the impact models that have been attempted before.

https://iopscience.iop.org/article/10.3 ... jlac8d96t1

For those on the fence about the Theia impactor theory, take a look at these simulations which are much more convincing than ever.

The models cited previously used approximately 1/1000 as many particles as this model did. The authors, Kegerreis et al., conducted a convergence study of this model by testing identical conditions with particle counts ranging from 10^5 to 10^8, and found that higher resolution models not only give categorically different results, but reveal many new insights about subsequent orbital evolution of the Moon by tidal influence, in varying amounts of stripping and accretion.

A total of 400 simulations were run with variations in both proto-Earth and Theia mass, velocity, angle, rotation, temperature, and composition. The efforts demonstrated a wide range of values for all of these parameters where the Moon would probably or possibly form, and with final parameters of size, composition, and angular momentum that reasonably match the real Moon.

There's also a very compelling animation video to watch!

http://icc.dur.ac.uk/giant_impacts/moon ... oudini.mp4

The authors (Kegerreis et al) were also aware of many questions in need of answers, especially the Moon's composition of silicates and isotopes. Referred to as a "crisis" in papers such as this one: https://royalsocietypublishing.org/doi/ ... .2013.0168 the new simulation study provides a mechanism for the material from Theia and proto-Earth (particularly their crusts) to mix very thoroughly. This phenomenon, too, may have been concealed by the earlier, low resolution simulation models. The core of Theia is almost entirely swallowed up by the Earth.

Evidence that the remains of the Theia impactor can still be detected in the Earth's mantle is being collected by another scientist, Qian Yuan, and you can read about his hypothesis here:
https://www.hou.usra.edu/meetings/lpsc2021/pdf/1980.pdf
They don't have a lot of data on that, yet, so stay tuned.

[notFritzArgelander]

Thanks for posting this. The simulation video is indeed quite compelling.

Earlier, in October, I had started a thread reporting on the same work. Unfortunately the videos there had lower resolution. However there were more simulation cases, four, including the one you linked. So interested folks might like to take a look at that one again.

viewtopic.php?t=27357

I especially like the point you make about resolving the isotope crisis.