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Life on Earth thanks to solar superflares?
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Geoscience
Embargo
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London: Monday 23 May 2016 16:00 (BST)
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New York: Monday 23 May 2016 11:00 (EDT)
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Tokyo: Tuesday 24 May 2016 00:00 (JST)
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Sydney: Tuesday 24 May 2016 01:00 (AEST)
An active young Sun could have helped to provide the early Earth with the ingredients and
climate required for life, according to a study published online this week in Nature Geoscience.
Nitrogen (N) is an essential component for the building blocks of life on Earth, but it is likely that it
was originally only available in the young Earth’s atmosphere in the form of molecular nitrogen
(N2) — which is not very chemically reactive. An energetic process would have been required to
break apart the nitrogen molecules in the atmosphere, so that nitrogen could then recombine in
more biologically useful forms.
Based on telescope observations of stellar storms on Sun-like young stars, in which massive
bursts of energetic particles are ejected, Vladimir Airapetian and colleagues hypothesize that a
similarly stormy young Sun could have unleashed frequent bursts of energetic particles towards
the Earth, and that these so-called superflares triggered changes to the early Earth’s
atmospheric chemistry. They estimate that such clouds of charged particles could have hit the
Earth frequently — perhaps more than once per day. Numerical simulations of the interactions
between the superflares and the Earth suggest that the superflares distort the Earth’s magnetic
field by creating large gaps around the poles, which provide pathways for the energetic particles
to penetrate the atmosphere.
The authors then find that the energetic solar particles interact with components of the Earth’s
atmosphere, including molecular nitrogen, to generate nitrous oxide (N2O) and hydrogen cyanide
(HCN). They suggest that the HCN could have provided a nitrogen source for building biological
molecules such as amino acids, and that the N2O — a potent greenhouse gas — could have
helped warm the Earth’s surface to a temperature that could support liquid water and the
beginnings of early life. This occurred at a time when the Sun, despite its storminess, was 30%
dimmer than it is today.
In an accompanying News & Views article, Ramses Ramirez writes that the proposed process
could have also influenced the environment on early Mars and, “may have implications for the
climates and potential biology of terrestrial exoplanets orbiting very young Sun-like stars.”
Article and author details
1. Prebiotic Chemistry and Atmospheric Warming of Early Earth
By An Active Young Sun
Corresponding Author
Vladimir Airapetian, Greenbelt
NASA, Goddard Space Flight Center, Greenbelt, Maryland, United States
Email: [email protected], Tel: +1 301 286 4014
News & Views Author
Ramses Ramirez, Ithaca
Cornell University, Ithaca, New York, United States
Email: [email protected]
DOI
10.1038/ngeo2719
Online paper*
http://nature.com/articles/doi:10.1038/ngeo2719
* Please link to the article in online versions of your report (the URL will go live after the embargo ends).
Geographical listings of authors
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United States