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Posted by George on August 11, 2007, 12:54 am
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>-> > Almost certainly, a planet that close to its star would have its
> -> > rotation tidally locked to its orbital motion. So one side of the
> -> > planet would have permanent "day", and the other half would have
> -> > permanent "night". The night side would probably be very cold, so
> -> > materials such as water would be frozen solid there. No water would
> -> > exist on the day side, since it would migrate to the night side and
> be
> -> > trapped there as ice. This doesn't seem to me to be a plausible home
> -> > for life - at least, not life similar to ours.
> -> >
> -> > dow
>
> -> Could there exist boundary conditions (such as near the terminator)
> which
> -> would allow liquid water? One would think it should be possible.
>
> -> George
>
> Well, if liquid water were to exist, its vapour would float through the
> atmosphere to the really cold area, where it would be frozen. So the
> liquid water would soon evaporate away.
>
> However, if the planet has a dense atmosphere, such as Venus's, it may
> transport heat around sufficiently well that there isn't much
> difference in temperature between the day and night sides. Venus's
> atmosphere, on the other hand, keeps the planet extremely hot because of
> a strong greenhouse effect. The same might well be true on this
> exoplanet. So the atmosphere *might* allow conditions to be right for
> liquid water all over the planet, or it might not.
>
> dow
Good points.
George
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