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suppose earth and venus switched places. will venus produce life?
Dorothy J Heydt wrote:
No. Venus's atmosphere is way the heck too thick, and a reducing atmosphere besides. It's thick now. It's far from certain that it was thick to begin with. Carbon dioxide may well have outgassed from rocks as the heat began to build. In other words, it may have been a case of positive feedback. And the Earth *had* a reducing atmosphere to begin with. It was partly the introduction of life that didn't depend on molecular oxygen and carbon dioxide that helped to convert the reducing atmosphere into an oxidizing one. The reason Earth has such a thin atmosphere compared to that of Venus is that quite early on, while the solar system was still in the final stages of assembly, proto-Earth was hit by a Mars-sized planetoid. There was molten rock flying all over the place; part of stony exterior of the planetoid went into orbit, regained a spherical shape, and became the Moon, while its heavy iron core sank into the Earth-mass and amalgamated with the Earth's core. In the process, a large part of Earth's primordial atmosphere was blasted away, leaving us with a much slighter greenhouse effect than Venus has. That's all plausible, but it's far from certain. I mean it's a pretty good bet that the Moon was created in such a cataclysmic collision, but it's not clear what that effect that would have had on the atmosphere. See above. Maybe, but not as likely. Chlorine, for instance, has sometimes been suggested, or silicon; but it's all speculation. Silicon, sure, but chlorine? How does one form chains with the single valence chlorine atoms? I can see some kind of organic molecule (and by organic I mean life-sustaining) involving chlorine, but I don't see how it can be based on chlorine. Do you have any details? -- Brian Tung The Astronomy Corner at http://astro.isi.edu/ Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/ The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/ My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html |
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suppose earth and venus switched places. will venus produce life?
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suppose earth and venus switched places. will venus produce life?
In article ,
Jasper Janssen wrote: On Sun, 14 May 2006 22:08:08 -0700 (PDT), (Brian Tung) wrote: Dorothy J Heydt wrote: No. Venus's atmosphere is way the heck too thick, and a reducing atmosphere besides. It's thick now. It's far from certain that it was thick to begin with. Carbon dioxide may well have outgassed from rocks as the heat began to build. In other words, it may have been a case of positive feedback. It doesn't really matter where it came from, all that matters is that it's there, and if you switch planets around you'll have to deal with it. And men would have to go two orbits over to meet women. /BAH |
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