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Habitable Exoplanet Found?

But, on Earth at least, it took a really long time before that initial life became large enough to be seen without a microscope. So if the planet in question was teeming with bacterial life, could we detect that?
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Sure. This is basically the goal of the Gaia Hypothesis (or at least where Lovelock started), and while I disagree with much of what Lovelock said I do agree that an unstable atmosphere (meaning that over time the atmosphere would change, and must be maintaned somehow) is pretty good evidence for life. If we're talking Earth-like life the presence of large amounts of oxygen would pretty much be proof (it likes to bond with things). A lack of oxygen isn't DISproof, but it'd be proof. And an unstable atmosphere is easy enough to detect--we look at the composition of atmospheres already.

It's not the size of hte organisms, but their influence on their environment. And honestly, single-celled beasties are better at influencing the environment than we large things are (you could cut down a significant portion of the trees without altering O2 levels too much, but if you get rid of phytoplankton you shut down the biosphere, for example). Simply put, there's a LOT more of them than there are of us.
 
Lovelock takes massive ****, but he is not stupid.
Nor is Sheldrake, for that matter.
 
The Lick-Carnegie Exoplanet Survey: A 3.1 M_Earth Planet in the Habitable Zone of the Nearby M3V Star Gliese 581

Abstract:

We present 11 years of HIRES precision radial velocities (RV) of the nearby M3V star Gliese 581, combining our data set of 122 precision RVs with an existing published 4.3-year set of 119 HARPS precision RVs. The velocity set now indicates 6 companions in Keplerian motion around this star. Differential photometry indicates a likely stellar rotation period of ~94 days and reveals no significant periodic variability at any of the Keplerian periods, supporting planetary orbital motion as the cause of all the radial velocity variations. The combined data set strongly confirms the 5.37-day, 12.9-day, 3.15-day, and 67-day planets previously announced by Bonfils et al. (2005), Udry et al. (2007), and Mayor et al (2009). The observations also indicate a 5th planet in the system, GJ 581f, a minimum-mass 7.0 M_Earth planet orbiting in a 0.758 AU orbit of period 433 days and a 6th planet, GJ 581g, a minimum-mass 3.1 M_Earth planet orbiting at 0.146 AU with a period of 36.6 days. The estimated equilibrium temperature of GJ 581g is 228 K, placing it squarely in the middle of the habitable zone of the star and offering a very compelling case for a potentially habitable planet around a very nearby star. That a system harboring a potentially habitable planet has been found this nearby, and this soon in the relatively early history of precision RV surveys, indicates that eta_Earth, the fraction of stars with potentially habitable planets, is likely to be substantial. This detection, coupled with statistics of the incompleteness of present-day precision RV surveys for volume-limited samples of stars in the immediate solar neighborhood suggests that eta_Earth could well be on the order of a few tens of percent. If the local stellar neighborhood is a representative sample of the galaxy as a whole, our Milky Way could be teeming with potentially habitable planets.

---- http://arxiv.org/abs/1009.5733

Heh yeah, "nearby" is maybe a little optimistic given our present technological level. But who knows? Maybe one day we will be out there running around in our avatar bodies and murdering innocent indigenous lifeforms. :P
 
Jim_MDP said:
"The chances for life on this planet are 100 percent," Steven Vogt, a UC professor of astronomy and astrophysics says. "I have almost no doubt about it."

What a silly thing for him to say.
I'm hoping there was a bit of quote mining.
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I, for one, welcome our new Gliesean overlords.
 
Light23 said:
Would living on a planet with more gravity than we're used to have any unwanted effects on our bodies?
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Given we already break bones just tripping (and old people break bones just standing there), I'm gonna guess yes :)
 
I think as far as gravity goes there is a kind of sweet spot with the minimum being something like .7g and the maximum being around 2g.

If the gravity is too low then the atmosphere will slowly be blow away by solar winds so that even if life develops it won't have much of a chance as only a few 100 million years later the atmosphere will be too thin to support it.

If the gravity is too heavy then liquids and gases would be divided into layers by density thereby reducing the chance of the chemical reactions needed for biogenesis.
 
Unless there were storms that mixed the layers. Any area where the layers mixed would provide an ideal spot for lifeforms to grow, sort of like how upwelling zones in our oceans are some of the most productive areas in the oceans.

I'll agree that a certain amount of atmospheric mixing would be necessary to start it, but after it's started? I'm not comfortabe saying "It can't happen".

Well, now that I think about it more I'm not willing to say it anyway--lithophiles prove that the atmosphere isn't the only place we have to look--but those will be very difficult to find from a few light-years away.
 
Dinwar said:
Unless there were storms that mixed the layers. Any area where the layers mixed would provide an ideal spot for lifeforms to grow, sort of like how upwelling zones in our oceans are some of the most productive areas in the oceans.

I'll agree that a certain amount of atmospheric mixing would be necessary to start it, but after it's started? I'm not comfortabe saying "It can't happen".

Well, now that I think about it more I'm not willing to say it anyway--lithophiles prove that the atmosphere isn't the only place we have to look--but those will be very difficult to find from a few light-years away.
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The point was that the higher the gravity the less mixing that storms can provide. So eventually there's a threshold where in order to mix the atmosphere the storms must be so violent that they would tear complex molecules apart making the formation of life a very unlikely occurrence.
 
readme.txt said:
http://news.sciencemag.org/sciencenow/2010/10/recently-discovered-habitable-world.html

???
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Why the question marks? Group A published the existence, based on ~11 years of their own observations together with 4 years of observation from group B. Group B took a closer look at their own data, now expanded to ~6 years, but couldn't find indication of another planet (which does NOT prove its non-existence, as they point out). Replication (by yourself, and other scientists) is a normal verification process in science. Currently, only group A's data shows the planet, hence some closer look is needed.
 
The chances of anything coming from GJ 581g are a million to one, they say.

Is there any way, now or in the foreseeable future, to check if it has a magnetosphere? That would certainly help life.

Fnord said:
"Starbucksesses"
;)
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I'd say "Starbucksen" but I'd reveal my OS of choice that way.
 
elgarak said:
Why the question marks? Group A published the existence, based on ~11 years of their own observations together with 4 years of observation from group B. Group B took a closer look at their own data, now expanded to ~6 years, but couldn't find indication of another planet (which does NOT prove its non-existence, as they point out). Replication (by yourself, and other scientists) is a normal verification process in science. Currently, only group A's data shows the planet, hence some closer look is needed.
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The ???'s were to get your attention. =)
 
The point was that the higher the gravity the less mixing that storms can provide. So eventually there's a threshold where in order to mix the atmosphere the storms must be so violent that they would tear complex molecules apart making the formation of life a very unlikely occurrence.
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Unless the life-forms are shielded by something. I'm thinking of the moon covered in ice, but which has liquid water under it. You can do whatever you want to the atmosphere, even have storms powerful enough to rip apart bacteria--but so long as the ice shell remains stable or semi-stable you're not going to affect the bugs under it. And once lithophiles evolve all bets are off. There's no storm powerful enough to affect the crust 2 miles down.

My point isn't that you don't have a valid point--you do. Looking for Earth-like life means looking in a very narrow window, and I think your restrictions in size are reasonable. My point is more that space is weird, and looking for Earth-like life, while the best shot we have (in that we know what to look for), certainly does not exhaust all the possabilities for life out there.
 
Dinwar said:
Unless the life-forms are shielded by something. I'm thinking of the moon covered in ice, but which has liquid water under it. You can do whatever you want to the atmosphere, even have storms powerful enough to rip apart bacteria--but so long as the ice shell remains stable or semi-stable you're not going to affect the bugs under it. And once lithophiles evolve all bets are off. There's no storm powerful enough to affect the crust 2 miles down.

My point isn't that you don't have a valid point--you do. Looking for Earth-like life means looking in a very narrow window, and I think your restrictions in size are reasonable. My point is more that space is weird, and looking for Earth-like life, while the best shot we have (in that we know what to look for), certainly does not exhaust all the possabilities for life out there.
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Space sure is weird. I think the "habitable zone" should be done away with. There is possible life on like 6 of the eight planets, plus many moons, regardless of "habitable zone". Perhaps this is wrongly slanted towards "undercrust oceans" which I'm becoming skeptical of--but distance and planet-size from star doesn't seem to be a major factor in possessing components of life. Apparently geochemistry matters more, even for a "dead" planet or moon.

So I withdraw my earlier post. Ganymede, Io, Europa, Iapetus, Mars, Neptune could well be our first conclusive ET life.
 
Jim_MDP said:
"The chances for life on this planet are 100 percent," Steven Vogt, a UC professor of astronomy and astrophysics says. "I have almost no doubt about it."

What a silly thing for him to say.
I'm hoping there was a bit of quote mining.
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I'm uncertain about the original source for the claim as regards quote mining, but I heard this fellow talking on NPR and was asked about this claim (about 2/3rd of the way through the clip.) He said something to the effect that if there were liquid water on the planet then he thought that there was at least a 99.999% chance that life had developed. Still a bold claim, and I'd love to know where people come up with their probabilities, but far more reasonable than the original quotation.
 
jasonpatterson said:
I'm uncertain about the original source for the claim as regards quote mining, but I heard this fellow talking on NPR and was asked about this claim (about 2/3rd of the way through the clip.) He said something to the effect that if there were liquid water on the planet then he thought that there was at least a 99.999% chance that life had developed. Still a bold claim, and I'd love to know where people come up with their probabilities, but far more reasonable than the original quotation.
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Frankly, I don't think that "99.999%" is a lot more reasonable than "I have almost no doubt about it." And I still think that he's making an unwarranted extrapolation from a single example.

Oh, well.

ETA: He did qualify it a bit by saying "I'm not a biologist, nor do I play one on TV." He based his belief on the observed ubiquity of life here (of course, I don't find that line of reasoning to be compelling).
 
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