If the Sun went out, would Earth cool to absolute zero?

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Fonapax Wex

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Fonapax Wex  asked the Naked Scientists:
Dear Dr. Chris,
I was once asked a question "If the sun were to go out, what would the temperature of the Earth be?" the answer is supposed to be 0 Kelvin. Is that about right?

What do you think?
« Last Edit: 21/12/2009 19:30:02 by _system »


Offline JP

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If the Sun went out, would Earth cool to absolute zero?
« Reply #1 on: 21/12/2009 20:59:54 »
The earth would cool only down to the background radiation temperature of the solar system.  This is because the earth is still being hit by light from distant stars as well as left over radiation from the big bang, and both of these heat the earth a tiny bit. 

The radiation left over from the big bang would heat the earth to about 2.7 Kelvin.  I'm not sure how much starlight would heat the earth, but its temperature would be lower than the coldest place in our solar system (a spot on our moon at ~35 K).  So the earth would eventually cool to between 2.7 K and 35 K.