[meteorite-list] Early Earth May Have Swallowed a Mercury-Like Planet
From: Shawn Alan <shawnalan_at_meteoritecentral.com>
Date: Wed, 15 Apr 2015 17:45:13 -0700
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Early Earth May Have Swallowed a Mercury-Like Planet
The jostling of the giant planets Jupiter and Saturn in the solar
system?s early days may have delivered a Mercury-type building block
to baby Earth, providing the planet with the chemistry to heat its
convecting, liquid metal core to this day, a new study shows.
The Mystery Of The Earth's Core Explained
We've been to the moon but we've barely scratched the surface of our own
The research, which is based on computer models, resolves two
long-standing mysteries about Mother Nature's recipe for Earth. The
first is why the planet has an abundance of the rare-earth metals
samarium (Sm) and neodymium (Nd) compared meteorites, which are believed
to be samples of Earth?s building blocks.
The second riddle is how the planet?s metallic core has stayed hot
enough over the eons to continue convection, a process that generates
Earth?s protective magnetic shield.
Oxford University researchers Anke Wohlers and Bernard Wood got the idea
to incorporate a sulfur-rich body like Mercury into Earth-formation
computer simulations after making connections between colleagues?
previous studies relating rare earth elements, including samarium and
neodymium, to sulfides; the elements? chemical mismatch between Earth
and meteorites; and observations from NASA?s MESSENGER spacecraft that
Mercury has high levels of sulfur.
?Then we had to do the experiments to test the idea,? Wood told
The models show the impacting body would have to have been 20 to 40
percent as big as Earth to produce the required chemical mix. The crash
could have happened as the building blocks for Earth were melding
together, or it could have been the hypothesized Mars-sized impactor,
named Theia, that hit Earth and led to the formation of the moon.
With Jupiter on the move, the inner solar system was like a ?mixing
bowl,? Wood said.
ANALYSIS: The Incredible Shrinking Mercury
?Under these circumstances, Mercury-like bodies could have been
scattered both outwards and inwards. One could envision an early
Mercury-like Earth or even a much later collision with a Mercury-like
body, such as that which formed the moon,? Wood wrote in an email.
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Received on Wed 15 Apr 2015 08:45:13 PM PDT