Habitable alien worlds ranked

The "freeze and fry" planets seem like the worst combination of extreme conditions for life. It's been calculated that atmospheric circulation could, in some cases substantially even out the extremes of temperature. This is what happens on Venus, which rotates so slowly as to be practically tidally locked. It's almost as hot all over the planet, as around the sub-solar point. They believe this could happen in much less dense atmospheres, too. Perhaps down to 1/10 the density of Earth's atmosphere. Given a planet well centered in its habitable zone, like Gliese 581 g is supposed to be, and tole... [More]

I think we truely have no idea what conditions life could manifest from distant planets. for instance a organic being that uses photosynthesis as a way of reciving energy and no need of eating for nutrition. just a thought.... but then you wouldnt need a atmosphere that has more oxeygen than carbon dioxide it would be vise versa. Like i said just a thought, in another galaxy the laws over there might be completly different from the laws over here.

meaningless. helpful as ever.

I think we truely have no idea what conditions life could manifest from distant planets. for instance a organic being that uses photosynthesis as a way of reciving energy and no need of eating for nutrition. just a thought.... but then you wouldnt need a atmosphere that has more oxeygen than carbon dioxide it would be vise versa. Like i said just a thought, in another galaxy the laws over there might be completly different from the laws over here. i suppose the question is whether there'd be likely to be the resources and the raw materials needed to build a technological Civilisation, and then... [More]

It's been calculated that atmospheric circulation could, in some cases substantially even out the extremes of temperature. This is what happens on Venus, which rotates so slowly as to be practically tidally locked. It's almost as hot all over the planet, as around the sub-solar point. Because it has a fluid and crushingly dense atmosphere that can't help but quickly conduct heat around the entire planet. They believe this could happen in much less dense atmospheres, too. I haven't read that and I can't find any example that supports that. Every model I've seen shows that thinner atmospheres aw... [More]

The Wikipedia article on Gliese 581 g has a reference to efficient heat transfer in even a 100 Millibar atmosphere, assuming sufficient greenhouse gases. There is also a link in the article to a scholarly article about this study. (footnote 23). link to the relevant section of the above Wikipedia article: http://en.wikipedia.org/wiki/Gliese_581_g#Tidal_locking_and_habitability see subsection on atmospheric effects, first paragraph.

I haven't read that and I can't find any example that supports that. Every model I've seen shows that thinner atmospheres away from the sun either quickly lose their heat to space before they can conduct it around the planet or trap the heat creating intense temperatures, depending on their distance from their sun. http://geosci.uchicago.edu/~rtp1/papers/Gliese581gPalletesApJL2011.pdf This paper here shows a model with Atmospheric pressure equal to Earth's with 20% CO2 mixed with N for Gliese 581g having a tempurature gradient of only 110 K between day/night sides.

http://geosci.uchicago.edu/~rtp1/papers/Gliese581gPalletesApJL2011.pdf This paper here shows a model with Atmospheric pressure equal to Earth's with 20% CO2 mixed with N for Gliese 581g having a tempurature gradient of only 110 K between day/night sides. Very strict (i.e. unlikely) conditions theoretically still resulting in a wide temperature variation by Earth standards.

Awwwee Can i go?

Very strict (i.e. unlikely) conditions theoretically still resulting in a wide temperature variation by Earth standards. How so? It's a larger planet than Earth so out gassing could easily account for such a CO2 concentration and Nitrogen isn't going to be uncommon in Exo-Atmospheres so I don't see any unlikely conditions and at best that temp. gradient is only 15-20° Kelvin greater than what we might typically see here on Earth and about 20° K less than record hot/cold temps. set on Earth.