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Updated Model Puts Earth On the Edge of the Habitable Zone

Unknown Lamer posted about a year and a half ago | from the living-on-the-razor's-edge dept.

Space 264

cylonlover writes with news of an update to the model used for calculating the habitable zone around stars shifting things out a bit. From the article: "Researchers at Penn state have developed a new method for calculating the habitable zone (original paper, PDF) around stars. The computer model based on new greenhouse gas databases provides a tool to better estimate which extrasolar planets with sufficient atmospheric pressure might be able to maintain liquid water on their surface. The new model indicates that some of the nearly 300 possible Earth-like planets previously identified might be too close to their stars to to be habitable. It also places the Solar System's habitable zone between 0.99 AU (92 million mi, 148 million km) and 1.70 AU (158 million mi, 254 million km) from the Sun. Since the Earth orbits the Sun at an average distance of one AU, this puts us at the very edge of the habitable zone."

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first (-1)

Anonymous Coward | about a year and a half ago | (#42791673)

piss!

They must have brought down the averages (5, Funny)

Anne_Nonymous (313852) | about a year and a half ago | (#42791693)

by deciding to include my neighborhood.

Different Stars.... different habitable zones? (0)

Wild_dog! (98536) | about a year and a half ago | (#42791713)

Could there be some variation? If another Star was slightly bigger or slightly smaller, wouldn't the habitable zones be different?

Re:Different Stars.... different habitable zones? (4, Informative)

pushing-robot (1037830) | about a year and a half ago | (#42791757)

They adjust the "habitable zone" for each star already.

Re:Different Stars.... different habitable zones? (0)

Anonymous Coward | about a year and a half ago | (#42792205)

Good to know.

Re:Different Stars.... different habitable zones? (4, Informative)

DragonWriter (970822) | about a year and a half ago | (#42791779)

TFS already indicates that the change affects where the Solar System's habital zone is calculated to be; even without looking at TFA it is clear that the "habitable zone" is star-specific.

Re:Different Stars.... different habitable zones? (1)

Wild_dog! (98536) | about a year and a half ago | (#42792351)

Thanks for the clarification

Re:Different Stars.... different habitable zones? (0)

Anonymous Coward | about a year and a half ago | (#42792877)

Habitable zone is not a fixed distance. It is a calculation based on several features each star possesses. So by definition it will be different for every star.

GW solution (5, Funny)

GrahamCox (741991) | about a year and a half ago | (#42791715)

This then suggests a simple fix for global warming - we just need to move Earth into a slightly higher orbit. A few hundred well-placed nuclear bombs ought to do it.

Re:GW solution (2)

fustakrakich (1673220) | about a year and a half ago | (#42791789)

No way! The temperature where I live is just right.. In fact, I wouldn't mind if the temps climbed a bit more.

Re:GW solution (2)

oodaloop (1229816) | about a year and a half ago | (#42791801)

A few hundred million, maybe. The earth is pretty big.

Re:GW solution (1)

MightyYar (622222) | about a year and a half ago | (#42791843)

What if each bomb were moon-sized? :)

Re:GW solution (1)

jackb_guppy (204733) | about a year and a half ago | (#42791927)

What if each bomb was let of on the moon instead? Each boom moves the Moon a little faarther out, pulling the Earth with it. I may a few centruies but we could move better position.

Though if they all went of together, we have "Space 1999" with a Moon size interplanetary ship. Will take awhile to get anywhere but at least we would be traveling.

Re:GW solution (1)

ldobehardcore (1738858) | about a year and a half ago | (#42792547)

I don't see how moving the moon into a higher orbit would change the earth-sun dynamic. If the moon's further away, it'll just have a smaller average tidal effect. It'll pull the earth less in all directions assuming the orbital eccentricity remains the same.

Re:GW solution (1)

viperidaenz (2515578) | about a year and a half ago | (#42792805)

It would change things quite a bit if the moon was pushed completely out of orbit. The mass of the earth-moon system would be significantly smaller if it were just earth.

Re:GW solution (3, Informative)

CrimsonAvenger (580665) | about a year and a half ago | (#42793059)

The mass of the earth-moon system would be significantly smaller if it were just earth.

Well, if you consider 98.8+% to be "significantly smaller" than 100%, then you're correct.

Otherwise, you might want to recheck your numbers....

Re:GW solution (0)

egamma (572162) | about a year and a half ago | (#42792989)

What if each bomb was let of on the moon instead? Each boom moves the Moon a little faarther out, pulling the Earth with it.

I'm sorry, I must have missed the string holding the earth and the moon together.

Re:GW solution (1)

oodaloop (1229816) | about a year and a half ago | (#42791937)

Do we have a lot of those in stock?

Re:GW solution (2, Informative)

Anonymous Coward | about a year and a half ago | (#42791849)

You probably mean more like our entire combined worldwide nuclear arsenal all going off at once in a single location.

Even then, I doubt it would have enough effect. The earth has been hit by countless enormous hunks of rock during its creation, each with power in the multitudes of times greater than our arsenal, and they didn't manage to move the world.

Re:GW solution (2)

PvtVoid (1252388) | about a year and a half ago | (#42791851)

This then suggests a simple fix for global warming - we just need to move Earth into a slightly higher orbit. A few hundred well-placed nuclear bombs ought to do it.

Let me guess: you fell for this [venehammerschlag.com] too.

Re:GW solution (4, Funny)

macraig (621737) | about a year and a half ago | (#42791881)

Nah... we just need a planet-sized pair of Stargates.

Re:GW solution (1)

girlintraining (1395911) | about a year and a half ago | (#42791945)

Nah... we just need a planet-sized pair of Stargates.

Worst. Plot. Ever.

Re:GW solution (1)

macraig (621737) | about a year and a half ago | (#42792041)

I'm writing the screenplay now. You want an option on it, then?

Re:GW solution (4, Funny)

girlintraining (1395911) | about a year and a half ago | (#42792789)

I'm writing the screenplay now. You want an option on it, then?

No, just have JJ Abrams direct it. It'll be my revenge.

Re:GW solution (0)

Anonymous Coward | about a year and a half ago | (#42791979)

We just need to have all of the robots go to the Galápagos Islands and point their exaust vents upward at the same time...

Re:GW solution (2)

viperidaenz (2515578) | about a year and a half ago | (#42792837)

If only we could get Bender to cooperate

Re:GW solution (5, Informative)

girlintraining (1395911) | about a year and a half ago | (#42792027)

A few hundred well-placed nuclear bombs ought to do it.

If the goal is a nuclear winter, sure. If you're trying to move the planet... how can I put this as succinctly as possible: If we detonated every nuke we had on one side of the planet, we'd succeed only in leaving one side of the planet uninhabitable. It wouldn't move the planet by any appreciable amount. The subsequent earthquakes would probably do more, by affecting spin. People seem to forget in orbital mechanics, to move in one direction, you have to displace an equal amount of mass x energy in the opposite direction. All a nuke would do is move the air around and leave a hole in the ground. Nothing would be ejected into space, and therefore, no movement.

I know you're trying to be funny, but after awhile, I get tired of the "a nuke is powerful enough to do anything!" thinking. I blame Bruce Willis.

Re:GW solution (4, Informative)

budgenator (254554) | about a year and a half ago | (#42792257)

I get tired of the "a nuke is powerful enough to do anything!" thinking. I blame Bruce Willis.

My Organic instructor was a real math geek, one day she demonstrated that a quarter inch of rain falling on Manhattan resulted in the same release of energy as the atomic bomb dropped on Hiroshima, she was good at estimating cube roots of 4 digit numbers in her head too.

Re:GW solution (2)

mister2au (1707664) | about a year and a half ago | (#42792485)

she was good at estimating cube roots of 4 digit numbers in her head too.

No great trick given there only a dozen or so integers that produce 4 digit results ... some basic gut feel for a cubic function will get you pretty close every time.

Re:GW solution (0)

Anonymous Coward | about a year and a half ago | (#42792641)

I tire equally of the "I saw it on TV" school of "the species must colonize the Galaxy" thinking.

Re:GW solution (0)

Anonymous Coward | about a year and a half ago | (#42792827)

How about 1000 TW of power plants running mass drivers timed to fire at a specific intervals in a precisely calibrated direction with a velocity of 30km/s over a period of a century? Would that move the orbit enough to change temperatures?

Global power production is about 5TW, so this would be a little bigger. Solar irradiance at Earth's surface is about is about 141,000 TW, so that power level is not impossible (requiring 11.3% of all land mass, deserts make up 33%) - even with solar thermal power. Nukes would be much more compact.

Any astrophysicists here? Would moving the Earth's orbit out potentially bring Mars closer, increasing its habitability as well? For anyone thinking really long term, it's relevant [sciencedaily.com] .

Re:GW solution (4, Informative)

Nimey (114278) | about a year and a half ago | (#42792165)

Niven's way ahead of you. It's a simple matter of knocking Uranus into a cometary orbit and using its gravity to move Earth further out.

Re:GW solution (0)

Anonymous Coward | about a year and a half ago | (#42792317)

Something tells me that moving a gas giant isn't much easier than moving a rocky inner planet.

Re:GW solution (1)

Nimey (114278) | about a year and a half ago | (#42792503)

Sure it is. The gas giant's atmosphere provides the fuel, and that's one of the hard parts.

Re:GW solution (4, Informative)

Dr. Spork (142693) | about a year and a half ago | (#42792707)

I thought the same thing, and then I thought: Not Niven, he wouldn't write something so dumb. So I googled and found this:

In Larry Niven's World Out of Time, somebody built one very big fusion ramscoop and dropped it into Uranus' atmosphere. It grabbed compressed hydrogen on the way down, then "bounced" back up to the upper atmosphere where it fired it all off in a directed fusion blast, which pushed it back down into the lower atmosphere where the whole process was repeated. Uranus was thus turned into a planetary gravity tug which was used to move Earth and Mars around (sun was heating up, I think -- it's been a few years).

(source [orbiter-forum.com] ) I don't think that would pass proper physics audit, but... there have been stupider ideas in scifi books.

Re:GW solution (1, Informative)

Anonymous Coward | about a year and a half ago | (#42793027)

what's dumb about it, the orbital mechanics were worked out. or maybe you didn't like his novel fusion drive?

anyway, during a war the sun was turned into a red giant by deliberate collision with giant asteroids. the earth was left in orbit around jupiter and Uranus moreover was used to pull Ganymede into Jupiter to ignite it in fusion so the Earth would have new star

Re:GW solution (1)

SternisheFan (2529412) | about a year and a half ago | (#42792463)

Niven's way ahead of you. It's a simple matter of knocking Uranus into a cometary orbit and using its gravity to move Earth further out.

I'm reading Larry Niven's "A World Out Of Time" now (after another slashdotter recomended it), and I'm almost where this is going to be explained. Good read so far, page 72 and it's already 3 million years into the future!

Re:GW solution (1)

pushing-robot (1037830) | about a year and a half ago | (#42792187)

Meh. All we need is a cable of sufficient length and tensile strength, two exceptionally strong anchors, and a mars rocket. Let angular momentum take care of the rest.

Re:GW solution (1)

viperidaenz (2515578) | about a year and a half ago | (#42792893)

You want to slow Earth down and plummet it into the Sun? Mars is traveling slower than Earth in a larger orbit with less mass...

Re:GW solution (1)

VortexCortex (1117377) | about a year and a half ago | (#42792523)

This then suggests a simple fix for global warming - we just need to move Earth into a slightly higher orbit. A few hundred well-placed nuclear bombs ought to do it.

Yes, but not a new idea. The slogan for Earth Day 2012 was "Mobilize The Earth": [earthday.org]

For Earth Day 2012 we are mobilizing the planet simply to say one thing: the Earth won't wait. It seems that environmental issues have been put on the back burner as we are in the midst of a global recession. It is time for us to Mobilize the Earth

However, I was disappointed when their implementation did not even begin to approach my own vision. [google.com]

Re:GW solution (1)

viperidaenz (2515578) | about a year and a half ago | (#42792897)

Did you just put a rocket booster in the south pacific? I am not impressed. That's going to lower property values.

Re:GW solution (1)

CRCulver (715279) | about a year and a half ago | (#42792681)

This then suggests a simple fix for global warming - we just need to move Earth into a slightly higher orbit.

Larry Niven already proposed this four decades ago in his novel Ringworld [amazon.com] , where the alien race the Puppeteers had moved their planets away from their sun to cool them. This was long before fears of global warming, but Niven felt that technological advancement would inevitably lead to problems with waste heat.

Easy calculation (4, Informative)

iris-n (1276146) | about a year and a half ago | (#42792777)

Hmm, not in my definition of "few hundred". The calculation is actually easy to make:

The earth is about 1,5E11 m away from the Sun, let's say that 1% is the variation that we want, so we get it to 1,515E11 m. So the difference in energy that we need is GMm(1/R1-1/R2) \approx 5E31 J; quite a lot.

The best (or worst, depending on your point of view) nuke we ever exploded is the Tsar Bomba [wikipedia.org] , which was 57 megatons or better 2,4E17 J.

So if we managed to use this energy with 100% efficiency (which we obviously can't) to move the Earth, we would need 10^14 nukes. Well, guess we're stuck here.

Re:GW solution (0)

Anonymous Coward | about a year and a half ago | (#42792799)

You just solved Social Security!

  How should we name the new months? PaulRyanuary?

Re:GW solution (1)

siride (974284) | about a year and a half ago | (#42792825)

Yes, and then when we screw it up, we'll need massive volcanoes to keep the poles cool while people live in squalor for a thousand years. Not what I'd like to see.

On Moving Earth's Orbit (1)

Tablizer (95088) | about a year and a half ago | (#42792885)

If we can get a small asteroid to gradually move a bigger asteroid around the solar system in a controlled orbit, then we could make such asteroid steal momentum from Jupiter or Saturn bit by bit to put Earth's orbit out a bit more. It would take several thousands of years, though. It's within our current technology because we just to use smaller objects to move & control progressively bigger objects by leveraging the big planets. It's somewhat similar to how we used Jupiter's gravity to speed up the New Horizons probe.

Well if a "scientist" makes a model then (-1)

Anonymous Coward | about a year and a half ago | (#42791735)

it MUST be correct.

With all the fluctuations over 4B years, how then have we remained in the zone to maintain life?

All scientific papers should be published with a full list of all grant money sources received over the past 24 months.

Re:Well if a "scientist" makes a model then (5, Insightful)

MightyYar (622222) | about a year and a half ago | (#42791869)

You're right, we shouldn't build models based on math. We shouldn't even try to understand the universe using such abstract tools. We should rely on thought experiments and push models around in sand. We can dress in togas and burn heretics.

Re:Well if a "scientist" makes a model then (0)

Anonymous Coward | about a year and a half ago | (#42791929)

Except TFA says "Our model does not include the radiative effects of clouds". So the model's means of calculating the effect of sunlight on ~50% of the planet's surface area is completely wrong.

Re:Well if a "scientist" makes a model then (1)

MightyYar (622222) | about a year and a half ago | (#42792251)

Wait, so he should have kept his work secret until he had the One Perfect Model?

Re:Well if a "scientist" makes a model then (3, Interesting)

ElectricTurtle (1171201) | about a year and a half ago | (#42792403)

He should not have published anything until his model matched up in some meaningful way with known facts about climate history. Obviously the lack of accounting for such a massive element is what probably is leading to this ridiculous idea that we're somehow almost too hot to support life, which is why we've had dozens of ice ages, including some which arguably devolved into 'snowball earth' scenarios where the virtually the whole planet was frozen. If your model doesn't fit major facts, it sucks, and it should be completely retooled at a minimum, or even discarded, because models that don't fit facts are nothing but incomplete masturbations.

Re:Well if a "scientist" makes a model then (1)

MightyYar (622222) | about a year and a half ago | (#42792661)

I would think there would be more empathy for a collaborative approach around here. What he is doing is the open-source equivalent of putting an early alpha up on GitHub. Hell, he even offers up the source code [washington.edu] .

Re:Well if a "scientist" makes a model then (1)

dryeo (100693) | about a year and a half ago | (#42792925)

You also have to take into consideration that the Sun is getting hotter, estimates are that it has got at least 25% hotter over the course of the life of the Earth. This is due to the ratio of helium to hydrogen changing causing the Sun to become more dense and therefore burn hotter. Estimates are that in as little as 500 million years the Earth will have its oceans boil and we'll become much more similar to Venus.
Then there are variations in the Earths orbit, variations in the layout of the continents as well as life itself. Photosynthesis surely lead to climate change and when those first forests grew without much to help them decompose there was massive amounts of carbon sequestration.
One of the lucky coincidences of Earth is that it has been inhabitable over most of its existence.
Another thing to consider is that the galaxy itself has habitable zone(s). Many stars have orbits that take them close to the core where radiation is much higher and the chances of a close enough encounter with another star to perturb planets orbit is much likelier. Same can be said about areas of the galaxy where massive star formation is happening.

Re:Well if a "scientist" makes a model then (1)

Sarten-X (1102295) | about a year and a half ago | (#42792315)

Damned right! Ron Paul 2016!

Re:Well if a "scientist" makes a model then (1)

OneAhead (1495535) | about a year and a half ago | (#42792177)

Umm... they are. Most granting agencies require scientists to do this.

Also, what exactly are you suggesting here? Big oil companies paid the scientists to place the earth at the hot edge of the habitable zone so that people would get more scared of it getting hotter? Or is this the "big solar" conspiracy theory again?

Energy output (0)

Anonymous Coward | about a year and a half ago | (#42791741)

Call me naive but doesn't the energy output of the star matter too? I would think a larger star with a higher energy output could/would have a habitable zone potentially much larger (greater diameter) than our own.

--AC

I'm glad we're at the warm edge (1)

nsteinme (909988) | about a year and a half ago | (#42791765)

Personally I would much have our global climate be what it is rather than have 40 degree oceans if we were further from the Sun.

Re:I'm glad we're at the warm edge (1)

dryeo (100693) | about a year and a half ago | (#42792995)

Why would moving further from the Sun warm the oceans? During much of the Earths history the oceans have been close to 40 degrees (80% is what I've read) but since humans have evolved during the current cold period it is questionable if we can survive in a world where the oceans are a couple of degrees above body temperature. Dinosaurs seem to have done well though.

The Orbit is too damn high! (1)

Anonymous Coward | about a year and a half ago | (#42791767)

I smell a new political platform to run on, this orbit is just too damn high!

Meaning at 1.5AU Mars Is In The Habitable Zone Too (3, Interesting)

Anonymous Coward | about a year and a half ago | (#42791791)

...time for some terraforming?

Re:Meaning at 1.5AU Mars Is In The Habitable Zone (0)

Anonymous Coward | about a year and a half ago | (#42791935)

Shucks, if only that were possible, eh?

Re:Meaning at 1.5AU Mars Is In The Habitable Zone (2)

suutar (1860506) | about a year and a half ago | (#42792183)

Well, given a thousand years or so we could probably dump enough asteroid material on it to bring the mass up. By then, we should have enough fusion tech to scarf hydrogen from Jupiter, fuse some of it up to oxygen, fuse more up to nitrogen, and combine the rest with some of the oxygen for water. Then seed with microbes, algae, etc; that ought to take another few hundred years. But after all that, sure, Mars ought to be nice.

And by the time that's done with we could probably set up a Nivenesque drive system on Neptune and use it to pull Venus out to the habitable zone and get started on it. :)

Re:Meaning at 1.5AU Mars Is In The Habitable Zone (2)

AK Marc (707885) | about a year and a half ago | (#42793047)

Nah, fission on Mars to split Fe to O2/N2. And we'd probably need to pull it into the asteroid belt to get all the asteroids to it, and we'd need nearly the entire belt to get it a noticeable gain in mass.

And I'd use the Niven drive to push all the gas giants together. See how star-like the result is. Then move that gas super-giant towards earth, and set Earth, Mars, Venus, and all the Jovian moons around, crashing Europa into Mars for the mass/water, and then using the Niven drive to move the small star-cluster into intergalactic space, if there ever is an issue with our Sun. (may have to do the Europa/Mars thing first, so as to not destroy Europa with the planet combining)

Mars (1)

Anonymous Coward | about a year and a half ago | (#42791865)

It also means Mars is just within the newly-defined habitable zone

Re:Mars (2)

mbkennel (97636) | about a year and a half ago | (#42791915)

If Mars had been significantly more massive and could retain a substantial atmosphere with greenhouse effect larger than Earth's, then it might have been habitable.

Re:Mars (2)

green1 (322787) | about a year and a half ago | (#42792215)

Considering the evidence we've been seeing recently for liquid water on the martian surface at some time in the past, it does stand to reason that Mars did at one point fall in the habitable zone.

Re:Mars (2)

Obfuscant (592200) | about a year and a half ago | (#42792887)

Considering the evidence we've been seeing recently for liquid water on the martian surface at some time in the past, it does stand to reason that Mars did at one point fall in the habitable zone.

Yes, Mars did have an atmosphere. Then some scientist tweaked his model which moved Mars to just on the other side of the tracks, and all the atmosphere vanished.

Mars (0)

Anonymous Coward | about a year and a half ago | (#42791917)

This puts Mars right in the middle of the habitable zone (1.38 AU)

Wonder how many other systems have multiple planets within the habitable zone.

Wow (5, Informative)

Arancaytar (966377) | about a year and a half ago | (#42791941)

The whole "Earth is fine-tuned for life" stuff has been debunked for ages (but still circulates thanks to creationists), but it's pretty amazing to consider our planet could be more than 1.5 times as far out as it is now, and still remain habitable.

Also, note that the Earth's perihelion places us at 0.983AU. If these numbers are correct, our orbit actually leaves the habitable zone for a brief period every year.

Re:Wow (1)

ColdWetDog (752185) | about a year and a half ago | (#42792417)

We're on the ragged edge of survival! The preppers are right!

Grab those guns, stock up on the freeze dried. Hunker down, it's gonna be a wild ride!

(Remember, this is a pretty soft call, lots of things in the model that aren't accounted for: clouds for one. Don't get all worked up just yet. In the end, we're our own worst enemy, the Universe is merely indifferent.)

Re:Wow (-1)

Anonymous Coward | about a year and a half ago | (#42792483)

Yeah, it's crazy how wrong those guys are. I mean, wholly fuck, we have found so much other life out there in the Universe. On the other hand, we have no such evidence so I guess you are wrong!

It's one thing to talk about science, it is quite another to take something abstract and twist it in to your own public display of bigotry. You really don't know any better than they do. Let me give you a hint: An appeal to emotion fallacy is why the majority of atheists hold their beliefs. You are most likely too ignorant to realize that, and sadly you were told you are so smart you shouldn't believe in _anything_. How does it feel to be a living oxymoron? And nah, don't answer that. Your bias and bigotry is already in full view, I'm just pointing out that you are a bigot.

Re:Wow (1)

vistic (556838) | about a year and a half ago | (#42792599)

They were making a valid point about how this would indicate we are not right in the middle of a goldilocks zone, which one would expect if creationism were true.

Then you went crazy. Quote a single word that indicated bigotry? The only hatred I see is in your rant.

Re:Wow (1)

Obfuscant (592200) | about a year and a half ago | (#42792951)

They were making a valid point about how this would indicate we are not right in the middle of a goldilocks zone, which one would expect if creationism were true.

Why would you expect that? There is no reason, other than an attempt at trying to prove a scientific explanation for something by trying to put artificial limits on the metaphysical one. You can't disprove creation by saying "it wasn't done the way I would have done it were I God", any more than you can prove something was done using a specific scientifically supported method by saying "that's how I would do it were I Isaac Newton."

Re:Wow (0)

Anonymous Coward | about a year and a half ago | (#42792717)

Well then, by that logic I maintain there is life at the center of the Earth. You ever been there? No? So how can you prove I'm wrong? BTW, I'm also selling prime real estate in the center of the Sun. Want to see pictures? No? Bigot.

Re:Wow (0)

Anonymous Coward | about a year and a half ago | (#42792565)

I don't find this so surprising.

What if tomorrow, extraterrestrials landed. The standard upheaval predicted by endless sci-fi movies occurred, and when the dust settled, we asked the first question:

"What took you so long to find us?"

And the answer:

"By our calculations, your Earth is outside of Sol's habitable zone."

What if, we evolved DESPITE Earth's conditions, and not as a cause of them?

[Stewie, stoned off his ass: What if the only reason we die, is because we accept it as an inevitability? *exhales in an exaggerated manner*]

Re:Wow (1)

AJWM (19027) | about a year and a half ago | (#42792703)

Congratulations! You've just solved the Fermi Paradox!

Well done, sir.

Re:Wow (0)

Anonymous Coward | about a year and a half ago | (#42792571)

First of all, these new claims don't really change anything.

In a very small sector of space, with very few observable dips in light (i.e.very few planets observed that transit between the Earth and that planets parent star), they have found at least 4 planetary candidates of Earth size (1.2 Earth Radius or less). Even correcting for changes in the HZ, there's probably a couple in there. The false positive rate (the % of planets that turn out not to be planets) is 9.5&, so there's more than likely at leas 1 planet already discovered that's in the habitable zone (whatever way you calculate). I expect confirmation of this later in 2013.

So, using very limited equipment, checking a very small area of space, and only planets that transit between our observation point and the parent star, there are more than likely millions of Earth size planets in the HZ of their parent stars in out galaxy alone.

One of the best reasons to focus on sun-like stars is because we know the most about them. We know they already have a track record for providing the conditions for Earth-like planets and also, perhaps more importantly, we know how old a star should be to support our planet. If we can find planets like ours in size orbiting sun-like stars, aged as old as our sun, the chances of finding a habitable planet surely go up.

But of course, life could exist in planets around the HZ of smaller stars, or much bigger ones, so it's certainly useful to have these models. Indeed, our planet isn't necessarily ideal for life. One could argue it would be better to be further out from a larger star, as it's more stable, orbits could be more stable, and less solar flares etc.

I'm not really as fascinated by finding intelligent life on any of these extrasolar planets if we ever do, as that prevents new problems and challenges, but to find a virgin Earth-like or Earth-similar that humans could one day inhabit is captivating to me.

Re:Wow (4, Informative)

dryeo (100693) | about a year and a half ago | (#42793061)

You do realize that the habitable zone has been moving out over the life of the solar system? The Sun converts hydrogen to helium, helium is more dense, increasing the density of the Sun causing it to burn hotter. Estimates are that some billion years ago the Sun was 25% cooler which would have shrunk the habitable zone quite a bit, perhaps to the point where Venus was habitable. Also with the Sun getting hotter, in perhaps half a billion years the oceans will boil and the Earth will be much more similar to Venus.

FTA (0)

Anonymous Coward | about a year and a half ago | (#42791943)

It's a study that evaluates the conditions optimal for an Earthlike, carbon-and-water-cycled ecosystem with no clouds (they do adjust for them, but modeling clouds would require serious time on big iron). Instead of just relying on "too hot" and "too cold" they're looking at things like greenhouse effects based on known absorption values and whether or not liquid water can exist on the surface, which brings the scope of this research into politically-sensitive AGW territory (they note that they deliberately underestimate the effects of CO2 as a greenhouse gas in this model). They also model for varying sizes of planets as well, like you'd expect, using both early Mars and recent Venus as prime examples of planets that stray from the habitable zone. All and all an interesting step forward for astronomers everywhere that owes a clear debt to ongoing climate change research here on Earth.

Sure (1, Insightful)

Exitar (809068) | about a year and a half ago | (#42791961)

Every month or so astronomers find something that, according to their knowledge, should not exist.
I bet they'll soon find a planet outside this new defined zone that has liquid water on its surface.

Re:Sure (4, Interesting)

Jason Levine (196982) | about a year and a half ago | (#42792453)

Surface? No, but Europa is believed to have an icy surface hiding a massive liquid water ocean. Although it is far from the habitable zone, gravitational interactions with Jupiter generates heat which keeps the oceans liquid. Add in some organic materials (which asteroids might supply) and life could have developed deep under the surface of Europa. Perhaps right now, as I type this, some big Europan fish-like creature is swimming through the cold oceans on the moon. (Or perhaps there are just Europan bacteria... even single celled alien life would be a major find.)

Mars (4, Interesting)

Eric Coleman (833730) | about a year and a half ago | (#42792549)

Mars had liquid water at some point and is outside the habitable zone, for some definitions of habitable zone. So it is entirely possible that planets with liquid water can exist outside the habitable zone. The real issue is with stability. An interesting take on this is to consider the flux of radiation from the Sun hitting the Earth. For a disk the size of the Earth, one can calculate the distance where water freezes and where water boils as a rough estimate of a "zone" of sorts. When looked at in this way, the Earth is at a point just barely above freezing. That we have the climate that we do beyond that near freezing point is due entirely to greenhouse effects.

Re:Sure (0)

Anonymous Coward | about a year and a half ago | (#42792729)

Well said!

But maybe later they'll find out why too. Maybe it will because the planet would be geologically very active and so provide a lot of it's own heat and fuel its own climate.

Or maybe it would be because of some new space wafer that exists that we know nothing about as you say.

What's fascinating, is that there's no reason why there aren't planets that sail through space alone with no sun and still provide conditions for life, they may be very active geologically, at least in parts, quite large, and who knows..maybe full of photo-florescent material, and beautifully illuminated. It might even be probable such a planet exists somewhere in the universe if not the galaxy, given the number of Earth and super-Earth sized planets we're finding with the Kepler mission.

But for Terraforming? (3, Interesting)

trims (10010) | about a year and a half ago | (#42792061)

This is interesting, since all the scientific data I've seen says that ultimately, Venus is far better than Mars as a target for Terraforming, yet this research is claiming that Venus is far outside the habitable zone, while Mars is smack in the middle of it.

Mars simply lacks two things: (1) the ability to generate a good strong magnetic field (too small, and no molten iron core), so it gets constantly bombarded with far more solar radiation than terrestrial life can stand outdoors, and (b) its much smaller mass and lack of magnetic field make is impossible for Mars to hold an atmosphere that's much more than it has now. So the result is that, while Mars superficially seems a better place for life now, there's no good way for us to transplant onto Mars without having to either live underground or under thick domes.

Venus, on the other hand, already generates a good magnetic field, and has no problem holding a significant atmosphere. It's just too hot and toxic. But a couple thousand tons of bacteria into the upper atmosphere will solve that problem, so Venus is actually the best candidate to turn into an Earth-like place.

I guess we'll have to look for two criteria: (1) which planets are most likely to have Earth-like indigenous life on them, and (2) which planets are best suited to be terraformed for occupation by us.

Like I said, interesting...

-Erik

Re:But for Terraforming? (1)

hsthompson69 (1674722) | about a year and a half ago | (#42792303)

So exactly how does one eliminate a high pressure atmosphere from Venus? One way of lowering the atmospheric pressure is reducing the mass of venus (thereby having weaker gravity, and unable to hold a high pressure atmosphere), but say you managed to instantaneously precipitate half of venus's atmosphere into solid form, and reduced its atmospheric pressure by half -> wouldn't its gravity tend to move the atmosphere back into a high-pressure equilibrium with the planet?

Re:But for Terraforming? (2)

Dr. Spork (142693) | about a year and a half ago | (#42792591)

You drop the temperature and all that atmosphere will come raining/snowing down. Probably the best way to drop the temperature is to unfurl a very large, semi-permiable membrane at the liberation point between Venus and the sun, to reduce the amount of solar flux reaching the surface. Eventually, we could do all that shading with a gigantic array of solar panels at L2 - just large enough so that the solar flux hitting the surface of Venus is the same amount as what hits the Earth (this requires 50% coverage). Yes, the long days and nights would be annoying, but I'm sure we'd adapt to it quickly.

Re:But for Terraforming? (0)

Anonymous Coward | about a year and a half ago | (#42793043)

Yes, the long days and nights would be annoying, but I'm sure we'd adapt to it quickly.

Holy shit, a day on Venus [lmgtfy.com] is 117 earth days long.

On that note, I'd like to take the week off!

Re:But for Terraforming? (0)

Anonymous Coward | about a year and a half ago | (#42792357)

I hope you're joking. Venus is a run-away furnace. It's the hottest place in the solar system (much hotter than Mercury due to its dense atmosphere). It's a searing, tormented planet. Please go and read

Furthermore the output of the sun us increasing. It's a giant reactor that will slowly consume the whole solar system. One day(billions of years from now) , even Mars will be too hot.

Re:But for Terraforming? (4, Interesting)

NalosLayor (958307) | about a year and a half ago | (#42792409)

Issues with removing the atmosphere aside:

1. I'm pretty sure that Venus doesn't have an appreciable magnetic field.

2. Even if it did, its day is about the same length in its year (e.g. about 250 earth days) so nobody could live in any fixed place on the planet without freezing or melting, even if we got rid of the thick atmosphere. You'd have to live in trucks rolling slowly around the planet in the ... pardon the pun ... twilight zone.

Mars on the other hand has normal days and could be warmed up with a greenhouse effect. Also, the thicker atmosphere would provide additional sheilding at the surface level. One could imagine the last few percentage points of shielding being made up with local magnetic field "bubbles" around settled areas, powered by fusion reactors, assuming we have that technology in the next century or so.

Re:But for Terraforming? (1)

erice (13380) | about a year and a half ago | (#42792517)

Venus, on the other hand, already generates a good magnetic field, and has no problem holding a significant atmosphere. It's just too hot and toxic. But a couple thousand tons of bacteria into the upper atmosphere will solve that problem, so Venus is actually the best candidate to turn into an Earth-like place

Venus doesn't have enough hydrogen to support hydrocarbon based life. Your cyanobacteria will simply die unless you hit Venus with a preposterous mass of comets. You may also need to get rid of the excess CO2 so your bugs don't they don't get too cooked.

Re:But for Terraforming? (4, Informative)

Svartormr (692822) | about a year and a half ago | (#42792907)

Alas, you are wrong about Venus. It has a negligible magnetic field (likely due to no core convection) and cosmic rays and the soloar wind freely interact with the upper atmosphere causing hydrogen loss. As well, if Venus was a black body and had no incoming radiation it would take on the order of 600+ years to cool off.

Magnetic Field + Mass != Habitable Zone (0)

Anonymous Coward | about a year and a half ago | (#42793049)

I know that was not your point, but just wanted to make sure that we are not confusing apples and oranges.

1-D toy model (1)

Nightlight3 (248096) | about a year and a half ago | (#42792285)

As the authors explain "Testing these predictions quantitatively using 3-D climate models should be a fruitful topic for future research." i.e. they need to keep paying mortgages, car loans,... next few years. The model is so embarrassingly inadequate, that considering how much room for fudging one has with toy models, they still barely managed to get Earth to come inside the "habitable zone."

I also wonder how will politicians translate this 1-D toy model into a story in which we are somehow responsible for the Earth's distance from Sun and need to pay them for it.

Re:1-D toy model (0)

Anonymous Coward | about a year and a half ago | (#42792999)

sorry mate but have you ever seen what goes in such simulations.
Feel free to write a more efficient 3d hyrdo code taking into account radiative processes and chemical interactions that doesnt want a million years per timestep on the biggest supercomputer on the planet and ill pay your mortgage myself

Dangerous Cooling (1)

BoRegardless (721219) | about a year and a half ago | (#42792431)

Simulation of being just a bit further away from the Sun sounds like it would effect what happened in the Maunder Minimum, with reduced Solar output where millions of people starved to death in Europe alone.

Huh? We're almost too close? (1)

maugle (1369813) | about a year and a half ago | (#42792861)

It seems he's saying that the Earth is almost too close to the Sun to sustain life, so I have to ask... are we talking about the same Earth here? You know, the one that's had dozens of ice ages?

Re:Huh? We're almost too close? (1)

BradleyUffner (103496) | about a year and a half ago | (#42792979)

It seems he's saying that the Earth is almost too close to the Sun to sustain life, so I have to ask... are we talking about the same Earth here? You know, the one that's had dozens of ice ages?

There is more to being habital than simply being in the habital zone.

Snowball Earth (1)

Tablizer (95088) | about a year and a half ago | (#42792935)

Wasn't Earth stuck in frozen-ice-ball phase about a billion years ago? If we were a little further out, we may still be stuck in that phase even today.

Maybe the habitable zone varies over time depending on the planet's conditions and chemical makeup.

Mars (0)

Anonymous Coward | about a year and a half ago | (#42792937)

A qucik look and Mars is 1.5 Au from the sun. I guess thats good enough! AWG solved just by moving next door!

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