Re: Life Atmosphere Basically the same everywhere? (resend)

On Dec 5, 12:47=A0pm, Lorentz <drosen0...@xxxxxxxxx> wrote:
On Dec 4, 1:24=3DA0pm, Tom Hendricks <tom-hendri...@xxxxxxx> wrote:> Ther=
e seems to be a major restriction on all life that many don't conside=3D

r. Only a planet about the size of Earth will hold in an atmosphere that =
wo=3D
uld lead to the origin of life. A planet with a larger atmosphere like Ju=
pi=3D
ter retains too much of the wrong gasses.
=A0 =A0 Are you sure about that? Maybe Jupiter has the exact right
atmosphere.
=A0 =A0 Also, I think you are wrong about the gravity of a planet having =
a
great affect on the composition of its atmosphere. All atmospheres are
unstable in an inverse square gravitational field. Eventually, all
atmospheres evaporate. The atmospheres with high molecular weight will
last longer than the ones with low molecular weight, to be sure.
=A0 =A0 =A0The composition would have more to do with age and temperature
than gravity. and maybe photochemistry. Then there is volcanic
activity... The gravity is only one factor.

Temperature is important but that just adds to the argument for Earth
size.
Jupiter is too hot and wrong atmosphere.
Moon is too cold and no atmosphere.
And we need water which equals 0-100C.. Yes we need planet in the HZ
habitable zone, but it seems to me to be pretty much earth size too.

Back to a planet reasonably close to the size of earth.

.

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