RussellMc wrote:
>> Of these, how many have
>> naturally occurring liquid water? Only two that I'm aware of, and the
>> second is mostly a guess because it is expected to have oceans under
>> ice.
>
> If "naturally occurring" includes having it carried in naturally by
> comets, then probably N.
>
> The lunar southern polar ice appears to lie in shaded areas at shallow
> depths or effectively on the surface from cometary deposition.

Note I was referring to *liquid* water.  This was a response to someone
claiming that the physical constants and such were all rather convenient,
and cited liquid water, room temperature, and the combination thereof as
evidence.

As I said in another message, not so rare existance of water (H2O) in a sta=
r
systems shouldn't be surprising.  However liquid water at "convenient" room
temperatures and pressures for human life is a different matter.

> One theory, perhaps not as much in vogue nowadays as once,  holds that
> earth's water supply is substantially augmented by the daily
> deposition of water into the atmosphere by micro water comets in the
> metres diameter size range.

The earth also has sufficient gravity such that it will have retained most
of its water over the last 4 1/4 billion years.  This is not the case for
Mars.

>> third almost certainly had liquid water in the past, but didn't have
>> the gravity to hold on to it over time. Now that would be rather
>> inconvenient to have the water you evolved to depend on evaporate
>> into space.
>
> This "third" is presumably Mars. While much water may well have been
> lost there also appears to be much left.

Yes there is good evidence of significant H2O still on Mars.  However, that
is quite certainly a small fraction of what there once was, and nobody has
found or is likely to find liquid water naturally occurring on the surface
of Mars today, at least not for very long.


********************************************************************
Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products
(978) 742-9014.  Gold level PIC consultants since 2000.
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.