Hey
buddies !
So,
what do we talk about today ? We're talking about
The
Moon : how did it form and why does it save us from glaciations ?
The
Moon formation deals with something I told you about 2 articles ago :
giants impacts.
Remember,
it is the period in Solar System formation scenario when planetary
embryos (which diameter is about few kilometres) are colliding and :
- are destructing completely and forming smaller bodies ;
- are fusioning and forming the four rocky planets we can see now.
One
of those impacts had a singular geometry : the one between the Earth
and another small body named Theia.
Theia
is a planetary embryo which would be formed in L5 Lagrange point (a
point of equilibrium in Earth's orbit). While it was growing, it lost
its equilibrium with the Earth, and was attracted by it. This is
summed up there :
The
impact between pro-Earth and Theia was so particular that the iron
core of Theia was absorbed by pro-Earth, and the rest, plus a part of
the Earth mantle, began to orbit around pro-Earth. This disk of
matter came to re-agglomerate to form the Moon.
A little animation to
understand these ideas :
So
then Moon was formed. Now, how can it save us from catastrophic
glaciations ?
It
goes that where the Moon is and how much mass it has implies a
gravitational force that stabilize the rotational axis of the Earth
on a lot of millenaries (something like 26 000 years). Now it has a
rotational axis of 23° with the elliptic plane, but it could go
between 0 and 90° without the Moon. Those irregular and chaotic
variations would imply extrem glaciations that would be lethal for
mankind. But the Moon is here, it protects us !
Moreover,
while it is orbiting around us and showing a big surface to the rest
of the Solar System, it protects us against most of asteroids and
comets that could impact us. Dinosaurs disappearance, does it come to
your mind ? Well, we could have been impacted by more than one if the
Moon was not there to protect us.
If
you are now convinced that the Moon is our shield, I made my job.
Well,
good bye, and next time we will deals with :
Space exploration : where
are we now ?
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