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ET 'habitable zone' is smaller than thought


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There are so many factors.  Lets say that Venus, with it's runaway greenhouse was out between Mars and Jupiter.  Quite possibly that would put it the right distance from the sun to support some form of more complicated life but at that same distance earth would be a lifeless ice world.

Edited by OverSword
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I believe that a large moon (like we have) is essential. it generates tides which seem to be great for life. Stirring the soup, as it were. It acts as a meteor shield, and it might even keep a core molten (again, via tidal forces) long enough for a stable magnetic field to form.
Personally, I believe complex life is rarer than the numbers of planets out there would make many assume.
I also believe that intelligent life is exponentially more rare.
Us having contact with said intelligent life is next to impossible, IMO. We might not technically be alone in the galaxy, but we might as well be, once everything (including time*) is accounted for.

*By this I mean when intelligent life develops the tech to send/receive signals like we can. Sure, right now, there could be thousands of planets with medieval civilizations, and there could be thousands more that are currently dead due to existential threats.

Edited by Seti42
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2 minutes ago, Seti42 said:

I also believe that a large moon (like we have) is essential. it generates tides which seem to be great for life. Stirring the soup, as it were. It acts as a meteor shield, and it might even keep a core molten (again, via tidal forces) long enough for a stable magnetic field to form.
Personally, I believe complex life is rarer than the numbers of planets out there would make many assume.
I also believe that intelligent life is exponentially more rare.
Us having contact with said intelligent life is next to impossible, IMO. We might not technically be alone in the galaxy, but we might as well be, once everything (including time) are accounted for.

You're absolutely right. And we are also very lucky to have an asteroid magnet close by, called Jupiter. It's gravitational pull has probably saved advanced life on Earth many times.

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2 minutes ago, sci-nerd said:

And we are also very lucky to have an asteroid magnet close by, called Jupiter. It's gravitational pull has probably saved advanced life on Earth many times.

That is so true. I forgot about our buddy and big brother Jupiter! Imagine how many comets from the outer solar system could have annihilated life on earth without it being there to hoover them up...

Edited by Seti42
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I might be completely wrong in this, but I think I agree with sci-nerd that there might be a lot of variables about which we might not even be aware of and that it's very difficult to gauge the possible conditions under which life in any form is possible, considering that right now we only have a sample size of one planet with life on it.

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I think we assume to know too much about life and how it forms. Saying that we know all about habitable zones and how big they are goes too far.

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2 hours ago, OverSword said:

There are so many factors.  Lets say that Venus, with it's runaway greenhouse was out between Mars and Jupiter.  Quite possibly that would put it the right distance from the sun to support some form of more complicated life but at that same distance earth would be a lifeless ice world.

Venus lost it's water because there was no large moon to act as a "counter control" on it's seas. Only the sun did and caused it to "tidally lock". Boiling them off. 

The large moon is the key to advanced life. Without that to keep a liquid core ( maintaining the magnetic field) and keep the planet's rotation and oceans stable. 

1 hour ago, sci-nerd said:

You're absolutely right. And we are also very lucky to have an asteroid magnet close by, called Jupiter. It's gravitational pull has probably saved advanced life on Earth many times.

Jupiter also cleared out the "Super-Earths/ Mini-Neptunes" allowing a planet just the right size and atmosphere density for the use of fire to form. 

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23 minutes ago, Piney said:

Jupiter also cleared out the "Super-Earths/ Mini-Neptunes" allowing a planet just the right size and atmosphere density for the use of fire to form.

Interesting! Do you have any sources to confirm that?

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5 minutes ago, sci-nerd said:

So Mercury, Venus, Mars and Earth could actually be made from the same debris?! Groovy!

Mercury was probably a gas giant that was stripped by the sun. It's core is way too big for it's size and it has a carbon coating. 

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4 hours ago, UM-Bot said:

According to a new study, many planets in the so-called habitable zone can only support single-celled organisms.

 

I always think stories like this are thinking too much inside the box. Is it not possible that life on a far-flung planet developed very, very differently and they could judge the earth inhabitable?

Edited by papageorge1
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1 hour ago, Piney said:

Mercury was probably a gas giant that was stripped by the sun. It's core is way too big for it's size and it has a carbon coating. 

Mercury is not close enough for solar winds to have stripped it were it a Hot Jupiter and the impact scaring suggests it's been in its current state since the late heavy bombardment period. It is thought, last I knew, to have been at least twice its current size in the past, perhaps losing that material to a large impact.

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There are a trillion other planets besides our earth in this galaxy and a trillion other galaxies.

I doubt we're alone  :-)

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5 minutes ago, Imaginarynumber1 said:

Mercury is not close enough for solar winds to have stripped it were it a Hot Jupiter and the impact scaring suggests it's been in its current state since the late heavy bombardment period. It is thought, last I knew, to have been at least twice its current size in the past, perhaps losing that material to a large impact.

Good point. 

I just went through some of the various theories and that is another point. It was twice it's current size and constant bombardments stripped it of it's mass. 

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6 minutes ago, Earl.Of.Trumps said:

There are a trillion other planets besides our earth in this galaxy and a trillion other galaxies.

 

Billions, and they still need to be just like Earth to develop advanced technology. 

Fire is the "key log". Without it, no metallurgy and you need just the right amount of oxygen and just the right amount of atmospheric density. 

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15 minutes ago, Piney said:

Billions, and they still need to be just like Earth to develop advanced technology. 

Let me see here....   We have about 200 billion stars in our galaxy. The opinions vary on how many planets per star, 4 is common. = 800 billion, not quite a trillion. . Ok, chainsaw me :)

An international team of astronomers, led by Christopher Conselice, Professor of Astrophysics at the University of Nottingham, have found that the universe contains at least 2 trillion galaxies, ten times more than previously thought.    galaxies link
Needless to say, this is controversial. Other estimates are more conservative

15 minutes ago, Piney said:

Fire is the "key log". Without it, no metallurgy and you need just the right amount of oxygen and just the right amount of atmospheric density. 

 

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2 minutes ago, Earl.Of.Trumps said:

Let me see here....   We have about 200 billion stars in our galaxy. The opinions vary on how many planets per star, 4 is common. = 800 billion, not quite a trillion. . Ok, chainsaw me :)

For metallurgy. Earth size planet around a sun like star and then the "anchor" (big moon) to keep everything in check.

That kind of knocks the statistics down a bit because you can have methane, nitrogen or water breathers but they still can't work metals. Just bang rocks. 

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8 minutes ago, Piney said:

That kind of knocks the statistics down a bit because you can have methane, nitrogen or water breathers but they still can't work metals. Just bang rocks. 

I've always had this weird idea about organic space craft that were grown. I blame the works of H.R. Giger for that.

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1 minute ago, XenoFish said:

I've always had this weird idea about organic space craft that were grown. I blame the works of H.R. Giger for that.

I did too but I blame Frank Herbert, the X-Men and being Native. We grew our fences, bows, and building material. I always wondered if we would've advanced in that direction.

In the X-men the Brood grew living starships.  

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1 minute ago, Piney said:

I did too but I blame Frank Herbert, the X-Men and being Native. We grew our fences, bows, and building material. I always wondered if we would've advanced in that direction.

In the X-men the Brood grew living starships.  

I often wonder what a species that focused solely on genetic engineering would be able to do. 

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hmmmph…  all I can grow is lint in my bellybutton  

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24 minutes ago, XenoFish said:

I often wonder what a species that focused solely on genetic engineering would be able to do. 

Well, that would take a few million years after the initial "spark" of the idea. We could do it far in the future. If we survive as a species, which I doubt. 

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I have no problem admitting that technological advanced species may be rare by % within the already (also probable) small % of planets with life, but I find hard to understand why people consider life to be rare, with this I mean that there is a good chance that in the grand scheme although life may be rare, its simultaneously abundant, it may not be everywhere but where it is is abundant in concentrated locations like....Earth (this is a belief not making or trying to make a factual statement).

Edited by godnodog
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