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Australia: The Land Where Time Began |
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Early Earth – Prebiotic Chemistry and Atmospheric Warming by an
Active Young Sun
Nitrogen is a critical ingredient of complex biological molecules
(Barrett& Elmore, 1998). However, the nitrogen which was outgassed into
the atmosphere of the early Earth (Ringwood, 1996) is relatively
chemically inert which required high temperatures for nitrogen fixation
into compounds which are chemically reactive to occur. According to
Airapetian et al. possible
mechanisms of nitrogen fixation include lightning, heating by
atmospheric shock caused by meteorites, and ultraviolet radiation from
the Sun (Summers et al.,
2012; Kasting, 1990). In this paper it is shown by Airapetian et
al. that nitrogen fixation in
the early terrestrial atmosphere can be explained by frequent, powerful
coronal mass ejection events from the young Sun, so-called superflares.
In this study it was found by the use of magnetohydrodynamic simulations
which were constrained by observations from the Kepler Space Telescope,
that successive superflare ejections produce shocks which accelerate
energetic particles, which compressed the magnetosphere of the early
Earth. Pathways resulting from extended polar cap openings for energetic
particles to penetrate into the atmosphere and, according to these
simulations of atmospheric chemistry, initiate actions which convert
molecular nitrogen, carbon dioxide and methane to nitrous oxide, which
is a potent greenhouse gas, as well as hydrogen cyanide, which is an
essential compound for life. Also, the destruction of N2, CO2
and CH4 suggests the stability of water on the early earth
cannot be explained by these greenhouse gases. Airapetian et
al. propose that
alternatively the efficient formation of nitrous oxide could explain a
warm early Earth.
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Author: M.H.Monroe Email: admin@austhrutime.com Sources & Further reading |