The Moon’s origins may be far different than we thought
▻https://massivesci.com/articles/moon-origin-new-theory-debris
We’re still learning the basic about Earth’s nearest neighbor
Theia-Terre, le choc frontal
/la-methode-scientifique-du-mardi-27-mar
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“This doesn’t look weird. This looks wrong,” [Simon Lock, a PhD candidate at Harvard University and the lead author of the study} remembers thinking. “What we were looking at was not what we thought we’d be looking at,” he says. “Through this whole process I have had to break my concept of what a planet is.”
Like many of us, he used to think of a planet as a “round, relatively cool body with a core and maybe a magma ocean” — not a giant rotating donut of vaporized rock.
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The Surprising State of the Earth after the Moon-Forming Giant Impact - Sarah Stewart (SETI Talks)
▻https://www.youtube.com/watch?v=PmhmWs71EMk
SETI Institute, publié 28.01.2015
In the giant impact hypothesis, the Moon accretes from a disk around the proto-Earth. In the canonical model, the impact also sets the present-day angular momentum (AM). Alternatively, the Moon may form via a high AM giant impact and the present-day AM was established by a lunar orbital resonance. I will discuss the unusual state of the Earth after a high angular momentum impact: a continuous pressure- and rotationally-supported fluid-to-vapor structure from the mantle to the disk. The surface of the structure cools radiatively and forms droplets. The droplets settle to the mid plane beyond the Roche radius and form moonlets. If mixing between the atmosphere and inner disk is efficient, then a wide range of high AM giant impacts may produce the isotopic similarity between the Earth and Moon.
~1h, cf.: ~ min 40!
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Et pour les francophones, réécouter sur france culture :
▻https://www.franceculture.fr/emissions/la-methode-scientifique/la-methode-scientifique-du-mardi-27-mars-2018
#radio
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