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(Space.com)   First Pluto, now the Goldilocks Zone. When I was a kid, it started at 0.95AU and we were happy   (space.com) divider line 8
    More: Interesting, habitable zones, planets, Arecibo, Goldilocks, planetary habitability, African Union, Gliese 581d  
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5269 clicks; posted to Geek » on 01 Feb 2013 at 11:30 AM (1 year ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2013-02-01 10:26:34 AM
2 votes:
At least it's not the Phantom Zone. That seems like it would be a real pisser.

www.scene-stealers.com
2013-02-01 09:45:00 PM
1 votes:

Tommy Moo: Why is liquid water necessary for life? Isn't this a paradigm? Of course a solvent medium is best for bringing together the ingredients necessary for the right chemical reactions to occur, so some form of liquid on the surface is likely necessary, but why couldn't there be an entire ecosystem that arises based on ammonia? It is a polar solvent, like water. Reactions might take longer at colder temperatures, but this would only mean that life would take a billion years to evolve to the same extent as 100 million earth years.


It is not that water is the only possibility for supporting life, just that we know life exists based on water, and we know what it looks like, and some of the conditions that allow it to develop. It's a lot easier to find something when you know what you're looking for.

Not only is there nothing to say that non-water based life may develop, but even water-based life may develop in ways we're not looking for. The habitable zone only applies to the possibility of surface water, but a variety of conditions may allow for water below the surface, or so tightly controlled by the ecosystem that it (in liquid form, at least) exists only within that ecosystem, or even for surface water to exist outside the habitable zone because of the planet's other unique characteristics.
2013-02-01 04:42:38 PM
1 votes:
Meh, I'm with one of the commenters on TFA. The habitable zone is a relatively narrow band from 0.99 AU to 1.67 AU for a Sol-type star, assuming:

...that all our knowledge about atmospheric dynamics applies to other planets. Oh, except they say they don't even consider clouds, so never mind, I guess.

...that "liquid water is stable on the planetary surface" is a hard and fast requirement for life. Never mind Earth's own deep biosphere, or all those microorganisms we've just found in the stratosphere, or deep-sea vents, etc, etc.

...that moons orbiting gas giants, heated by tidal effects and perhaps even by thermal radiation from the gas giant itself, don't count.

...that Earthly biochemistry, with our particular fragile proteins and sugars, is the only possible path to life.

...that life even needs to be water-based. Ammonia-based lifeforms shudder at the thought of an environment saturated with toxic, corrosive hydroxylic acid. Critters who've evolved from the rich, dynamic environment of a stellar convective zone probably aren't even aware of such extreme low-temperature phenomena as "chemistry".
2013-02-01 03:33:45 PM
1 votes:

Tommy Moo: Why is liquid water necessary for life? Isn't this a paradigm? Of course a solvent medium is best for bringing together the ingredients necessary for the right chemical reactions to occur, so some form of liquid on the surface is likely necessary, but why couldn't there be an entire ecosystem that arises based on ammonia? It is a polar solvent, like water. Reactions might take longer at colder temperatures, but this would only mean that life would take a billion years to evolve to the same extent as 100 million earth years.


You are absolutely right, it doesn't necessarily have to be water.  Ammonia and water are both protic solvents and in fact life as we know it (from a biochemistry stand point) could have developed in either.  Our biochemistry is just much more efficient in water (the argument of cause-or-effect/chicken-or-egg can be left up to others).  The fact that both ammonia and water can donate and accept protons is the key.  In a similar fashion, there could even be a whole ecosystem based in ethanol; perhaps called fark.
2013-02-01 12:08:50 PM
1 votes:
Why is liquid water necessary for life? Isn't this a paradigm? Of course a solvent medium is best for bringing together the ingredients necessary for the right chemical reactions to occur, so some form of liquid on the surface is likely necessary, but why couldn't there be an entire ecosystem that arises based on ammonia? It is a polar solvent, like water. Reactions might take longer at colder temperatures, but this would only mean that life would take a billion years to evolve to the same extent as 100 million earth years.
2013-02-01 11:56:07 AM
1 votes:
Mars is no place to raise your kids.
2013-02-01 11:44:59 AM
1 votes:

MindStalker: simplicimus: Apparently Earth is outside the habitable zone, at the zone begins at .99 AU.

We get as close as 0.98329134 AU.

But that's when the Zombies come out.


Facebook AU burn

scienceblogs.com

Dont tell me I'm wrong ever again!
2013-02-01 09:18:03 AM
1 votes:
Whew, just made it.

i.space.com
 
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