A New Earth?

On May 2, 12:37 pm, "Greg Neill" wrote:
"Market Theory" wrote in message

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On Apr 30, 9:15 am, Mitchell Jones wrote:
Here's an interesting link:

http://www.dailymail.co.uk/pages/liv...ogy/technology....
?in_article_id=450467&in_page_id=1965

I did a quick calculation of the surface gravity, based on the following
inputs:

M is the mass of Glise581cwhich, according to the article, is 5 times
as massive as Earth. The mass of Earth is 5.9736x10^24 kg. G =
6.6742x10^-11. The radius of Glise581c, converted to meters, is r =
9,656,083.

I hope you realize that noone has a clue what the radius of 581c is.
The number 1.5 is someone's guess based on the mass and the hope that
the planet is rocky.

A more serious problem is that the planet receives 244% of the star
light that Earth does, or about 25% more than Venus. If it had water
it would be way past the runaway greenhouse threshold. I estimate the
surface temperature assuming an equilibrium steam atmosphere of about
830K.

Your estimate does not accord with the estimate made by
the investigators, who put the temperature in the range
of liquid water.

The investigators have to make a name for themselves. Time will tell
whose estimate is better. Have a look at http://arxiv.org/PS_cache/astro-ph/p.../0303186v2.pdf
and tell me what you think.

cheers,
--mt.

"Market Theory" wrote in message
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On May 2, 12:37 pm, "Greg Neill" wrote:
"Market Theory" wrote in message

oups.com...





On Apr 30, 9:15 am, Mitchell Jones wrote:
Here's an interesting link:


http://www.dailymail.co.uk/pages/liv...ogy/technology....
?in_article_id=450467&in_page_id=1965

I did a quick calculation of the surface gravity, based on the
following
inputs:

M is the mass of Glise581cwhich, according to the article, is 5
times
as massive as Earth. The mass of Earth is 5.9736x10^24 kg. G =
6.6742x10^-11. The radius of Glise581c, converted to meters, is r =
9,656,083.

I hope you realize that noone has a clue what the radius of 581c is.
The number 1.5 is someone's guess based on the mass and the hope that
the planet is rocky.

A more serious problem is that the planet receives 244% of the star
light that Earth does, or about 25% more than Venus. If it had water
it would be way past the runaway greenhouse threshold. I estimate the
surface temperature assuming an equilibrium steam atmosphere of about
830K.

Your estimate does not accord with the estimate made by
the investigators, who put the temperature in the range
of liquid water.

The investigators have to make a name for themselves. Time will tell
whose estimate is better. Have a look at
http://arxiv.org/PS_cache/astro-ph/p.../0303186v2.pdf
and tell me what you think.

I think that investigators who publish in the literature won't
retain their credibility for long if they espouse figures that
are easily shown to be wrong, merely to make a short-lived
splash in the media.

I would have to see their estimates for albedos and opacities
at different wavelengths to see whether their conclusions are
justified. I suspect that their peers are quite capable of
running the numbers too, and I haven't seen any major objections
appear.

"Greg Neill" wrote in message
m...
"Market Theory" wrote in message
ups.com...
On May 2, 12:37 pm, "Greg Neill" wrote:
"Market Theory" wrote in message
oups.com...
....
A more serious problem is that the planet receives 244% of the star
light that Earth does, or about 25% more than Venus. If it had water
it would be way past the runaway greenhouse threshold. I estimate the
surface temperature assuming an equilibrium steam atmosphere of about
830K.

Your estimate does not accord with the estimate made by
the investigators, who put the temperature in the range
of liquid water.

The investigators have to make a name for themselves. Time will tell
whose estimate is better. Have a look at
http://arxiv.org/PS_cache/astro-ph/p.../0303186v2.pdf
and tell me what you think.

I think that investigators who publish in the literature won't
retain their credibility for long if they espouse figures that
are easily shown to be wrong, merely to make a short-lived
splash in the media.

I would have to see their estimates for albedos and opacities
at different wavelengths to see whether their conclusions are
justified. I suspect that their peers are quite capable of
running the numbers too, and I haven't seen any major objections
appear.

I haven't read that particular page but other articles
make it clear the temperature being discussed is the
equilibrium (black body ?) temperature at that distance
from the star and takes no account of environmental
effects. A perfectly professional approach when the
detail is known.

George