[meteorite-list] Scientists find most Earth-like planet yet

From: Francis Graham <francisgraham_at_meteoritecentral.com>
Date: Wed, 25 Apr 2007 12:15:53 -0700 (PDT)
Message-ID: <388374.90066.qm_at_web58707.mail.re1.yahoo.com>

--- valparint at aol.com wrote:

> The composition of the atmosphere is critical to
> knowing the temperature
> of the planet - think Venus vs. Mars. If they didn't
> directly see the
> planet there is no way they can know anything about
> its atmosphere.
>
> Paul Swartz

  Venus became hot by loss of its water vapor. An
early high convective troposphere carried Venus' water
vapor to altitudes where solar UV would dissociate it,
thus there was no water to dissove the carbon dioxide
into oceans and then lock it in sedimentary rock. On
Earth, a Venusful of carbon dioxide is locked in
limestone--the most abundant sedimentary rock. Our
troposphere did not extend high enough to
photodissociate the water vapor.
  What happened on Venus cannot happen on this new
planet because a red dwarf star does not produce
enough UV.
  Still, there are many possibilities otherwise than a
New Earth, so Paul's point is well taken even if he
used the wrong counterexample. I would be much more
salivating if they detected--as the said they may in
the future--water.

Francis





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Received on Wed 25 Apr 2007 03:15:53 PM PDT