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Posted by Jonathan Silverlight on February 18, 2006, 6:41 pm
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>-> If I was really keen I'd work out the mass equivalent of the solar
>-> energy falling on the Earth, as that is apparently seriously proposed,
>-> but for now I'll let someone else shoot at this fish in a barrel.
>
>Should be easy. The solar radiation flux at Earth is about 1 kilowatt
>per square metre. The radius of the Earth is about 6.4e6 metres, so the
>area its disk presnts to the sun is about pi x 6.4^2 e 12 m^2, or about
>1.2e14 m^2. So about 1.2e17 (let's call it 1e17) watts of solar energy
>are intercepted by Earth. e = m.c^2, so m is e / c^2, or 1e17/(3e8^2),
>which comes pretty close to 1. So the solar energy that strikes the
>Earth has a mass of about one kilogram per second.
>
>About the same amount is lost by radiation to space, so the net change
>of Earth's mass from this cause is much less than 1 kg/s. But, even if
>there were no loss to space, the effect would be small.
Thanks. Didn't I recently read that the amount of radiation lost to
space is currently slightly less than the input, which is distinctly
scary? :-)
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