
A Violent Splash of Magma That May Have Made the Moon - RainforestCx
https://www.nytimes.com/2019/05/01/science/moon-earth-collision.html
======
dessant
Why does the Moon fall back to Earth at the end of the simulation?

~~~
YeGoblynQueenne
Also, if you play the animation slowly, you can see a brighter circle forming
at the point of impact, before the impact. Is that part of the simulation or
an artifact of the animation, I wonder?

~~~
magicalhippo
My interpretation is that the surface magma, cooled down hence the dull
orange, is blown away by the bow shock in the atmosphere from the other body
entering the atmosphere. This exposes the hotter, brighter, underlying magma.

Could of course be entirely wrong.

~~~
mcherm
Wouldn't that require an unreasonably thick atmosphere? Our current atmosphere
is only around 10 miles high. (Obviously, it all depends on what you consider
as your cutoff.)

~~~
magicalhippo
Possibly, I'm no expert.

I didn't think about timescale though, the bow shock would require very short
timescale (if at all plausible like you said).

If it happens on longer timescales, then maybe it's just surface heating from
the emission of the other body.

------
Sharlin
A question I’ve been wondering about: To what extent is the contemporary
Earth’s crustal composition a mix of Theia and the proto-Earth? If Theia was
roughly one tenth of Earth by volume, where did all that matter end up?

------
tengbretson
This model puts the composition of the moon at around a 70:30 mix of Earth to
Theia. This doesn't square with titanium composition of the moon rocks that
indicate that the moon was formed from _cooled_ earth materials.

[https://www.wired.com/2012/03/moon-formation-
collision/](https://www.wired.com/2012/03/moon-formation-collision/)

------
tigerlily
I wonder how much bigger the Earth would have been if it hadn't been smashed
by a planetesimal? (Assuming the theory is true).

~~~
dpark
Presumably Earth would be smaller without the impact. Mars-sized matter was
added to the Earth as a result of the impact and all that was lost was the
moon (and perhaps some smaller amount that escaped entirely).

------
dontbenebby
Reading about things like this (matter ejected from Earth into space) + recent
research on extremophiles makes wonder if panspermia might be an accurate
theory:

[https://en.wikipedia.org/wiki/Panspermia](https://en.wikipedia.org/wiki/Panspermia)

~~~
Boulth
According to Neal deGrasse Tyson (source: his recent books and I think I've
heard it on his YT channel too) it is quite possible that early Mars had
better conditions for life than early Earth and that life could travel to
Earth from there.

------
starvingbear
They should also account for the possibility that the moon rocks are actually
from earth. Just in case the moon landing was faked

