[karajorma]

What's wrong with talking about habitable zones?  Sure, just because a planet is within the "habitable zone" doesn't mean it is actually habitable, nor does a planet being outside that zone make it necessarily uninhabitable.  But the zone does give us a good indication of whether or not the planet is able to sustain liquid water on the surface.

If you're talking about a planet that is suitable for human colonisation that might be an issue. But when people talk about habitable zones they are usually talking about them possibly having life already on them.

When it comes to the Solar System, apart from Earth we have at least a couple of good candidates for life (Mars and Europa) and a few more outliers (Titan, etc). Notice that of those, none are actually in the habitable zone for Sol. So given that we can already envision there being a good possibility of life on bodies outside of the habitable zone within our own system it always confuses me why the hell people insists that they are a requirement for finding life outside of it.

[SypheDMar]

Because, if you're searching for life outside the Earth, you want to increase your chances as much as you can, so you search in highly probably places instead of less probable and less obvious. You can't, for example, find life on a Titan-like exoplanet easily yet. Even if the same is true for the new exoplanet, it gives us hope.

[Nuke]

say in a hundred years we come up with a feasible engine technology that can go up to 1/4 the speed of light, but only for a small probe, and assume weve solved the problem of extremely long range communications. that would put the journey to the planet in question into the time frame of about 80 years, and another 20 years for the data to return to earth. say such a probe costs 10 trillion dollars. you want to be damn sure you send this probe to somewhere you think to have a high probability of supporting life. otherwise youd be wasting 10 trillion.

of course by the time such a mission were carried out, there would likely be a very long list of potential candidates, from decades of even centuries of exoplanet detection. your first concern would be range, you would go look at closer planets first. the ones at a distance might be beyond your probe's capabilities, or beyond your sphere of interest (too far for human colonization), and would take longer to receive data from them. then you would look at all the factors that seem good for life. is it in the habitable zone? is the gravity close to earth gravity? does it rotate (rotating planets would have a higher probability than non rotating planets perhaps)? does it have a magnetic field? and so on. youd send the probes to the ones which have the most positive results, and not the iffy star systems. that does not mean that any of those had life, or that anything that seemed unlikely would have plenty. its just you want to look at all your options and pick the best one.

[Liberator]

Wasn't a religion bash, was a creationist bash. I really am very curious about what their explanation is going to be.

So because of the laws of physics, chemistry and biology, you reject the concept that it was all created, at some time in the past, by an all knowing, all powerful, ever present, all merciful God?

[General Battuta]

Wasn't a religion bash, was a creationist bash. I really am very curious about what their explanation is going to be.

So because of the laws of physics, chemistry and biology, you reject the concept that it was all created, at some time in the past, by an all knowing, all powerful, ever present, all merciful God?

I don't think there's any reason to say that's impossible; in fact it's thoroughly possible. It's just not testable or useful, and there's no evidence for it (nor will there ever be evidence for or against it).

And the possibility of the act of creation is independent from the possibility that the creating entity was a single, anthropomorphic, merciful God. Unfortunately it's just as possible that it was all created by a disinterested clockmaker entity or entities, or a malevolent entity that feeds on our suffering, or a geek running a server farm in another universe, or a tooth fairy.

All these scenarios are equally likely, equally untestable, and equally irrelevant to the pursuit of scientific progress and the betterment of the human condition.

[Bobboau]

So because of the laws of physics, chemistry and biology, you reject the concept that it was all created, at some time in the past, by an all knowing, all powerful, ever present, all merciful God?

no she rejects it because it's implausible.

[redsniper]

NO! Stop it now! I do NOT want to see such an exciting thread turned into yet another HLP religion flamewar. This should be about Gliese 581g and how we plan to invade. Do NOT **** this up with the same tired old arguments that never end.

[General Battuta]

I will usher iamzack and Liberator to a private room if they want to continue their foreplay.

[SpardaSon21]

This should be about Gliese 581g and how we plan to invade.

We should nuke the major population centers from orbit, then deploy a magic anti-radiation nano-swarm and force the remaining inhabitants to bow before the benevolent rule of the Terran Empire with our elite power-armored infantry Heinlein would be jealous of.

[NGTM-1R]

This should be about Gliese 581g and how we plan to invade.

Who said anything about invasion? The RKV has been deployed. The planet will be habitable again, but nicely uninhabited, in approximately 1000 years

[karajorma]

say in a hundred years we come up with a feasible engine technology that can go up to 1/4 the speed of light, but only for a small probe, and assume weve solved the problem of extremely long range communications. that would put the journey to the planet in question into the time frame of about 80 years, and another 20 years for the data to return to earth. say such a probe costs 10 trillion dollars. you want to be damn sure you send this probe to somewhere you think to have a high probability of supporting life. otherwise youd be wasting 10 trillion.

of course by the time such a mission were carried out, there would likely be a very long list of potential candidates, from decades of even centuries of exoplanet detection. your first concern would be range, you would go look at closer planets first. the ones at a distance might be beyond your probe's capabilities, or beyond your sphere of interest (too far for human colonization), and would take longer to receive data from them. then you would look at all the factors that seem good for life. is it in the habitable zone? is the gravity close to earth gravity? does it rotate (rotating planets would have a higher probability than non rotating planets perhaps)? does it have a magnetic field? and so on. youd send the probes to the ones which have the most positive results, and not the iffy star systems. that does not mean that any of those had life, or that anything that seemed unlikely would have plenty. its just you want to look at all your options and pick the best one.

Cart before the horse. We should have checked out both Mars and Europa properly by then. By which point we'd have a much better understanding of exactly where is the best place to find life.

Bear in mind that the possibility exists that Earth-type planets could actually be less likely to have life than cold worlds like Europa. The warmth could make it more likely that self-replicating molecules would be broken down before they could form. It could just as easily mean the opposite.

The point is that it's ridiculously premature to go on about habitable zones being the best place to look for life since our data set on what makes a planet likely consists of one point.

[Nuke]

say in a hundred years we come up with a feasible engine technology that can go up to 1/4 the speed of light, but only for a small probe, and assume weve solved the problem of extremely long range communications. that would put the journey to the planet in question into the time frame of about 80 years, and another 20 years for the data to return to earth. say such a probe costs 10 trillion dollars. you want to be damn sure you send this probe to somewhere you think to have a high probability of supporting life. otherwise youd be wasting 10 trillion.

of course by the time such a mission were carried out, there would likely be a very long list of potential candidates, from decades of even centuries of exoplanet detection. your first concern would be range, you would go look at closer planets first. the ones at a distance might be beyond your probe's capabilities, or beyond your sphere of interest (too far for human colonization), and would take longer to receive data from them. then you would look at all the factors that seem good for life. is it in the habitable zone? is the gravity close to earth gravity? does it rotate (rotating planets would have a higher probability than non rotating planets perhaps)? does it have a magnetic field? and so on. youd send the probes to the ones which have the most positive results, and not the iffy star systems. that does not mean that any of those had life, or that anything that seemed unlikely would have plenty. its just you want to look at all your options and pick the best one.

Cart before the horse. We should have checked out both Mars and Europa properly by then. By which point we'd have a much better understanding of exactly where is the best place to find life.

Bear in mind that the possibility exists that Earth-type planets could actually be less likely to have life than cold worlds like Europa. The warmth could make it more likely that self-replicating molecules would be broken down before they could form. It could just as easily mean the opposite.

The point is that it's ridiculously premature to go on about habitable zones being the best place to look for life since our data set on what makes a planet likely consists of one point.

we do need more data, its true. but if we find alien germs on mars and alien fishies on europa, its still not that much data to go on. we may have to expand the habitable zone and include moon systems of large gas giants. still mars isnt exactly teeming with life, and we need more data on europa. but as it stands the habitable zone has the highest probability. we need to discover life elsewhere before we can improve upon the known the planetary requirements for life. if we had the technology today to send a probe to a star system like the one discussed in this thread, we would look for a system with a planet much like our own.

[Bob-san]

say in a hundred years we come up with a feasible engine technology that can go up to 1/4 the speed of light, but only for a small probe, and assume weve solved the problem of extremely long range communications. that would put the journey to the planet in question into the time frame of about 80 years, and another 20 years for the data to return to earth. say such a probe costs 10 trillion dollars. you want to be damn sure you send this probe to somewhere you think to have a high probability of supporting life. otherwise youd be wasting 10 trillion.

of course by the time such a mission were carried out, there would likely be a very long list of potential candidates, from decades of even centuries of exoplanet detection. your first concern would be range, you would go look at closer planets first. the ones at a distance might be beyond your probe's capabilities, or beyond your sphere of interest (too far for human colonization), and would take longer to receive data from them. then you would look at all the factors that seem good for life. is it in the habitable zone? is the gravity close to earth gravity? does it rotate (rotating planets would have a higher probability than non rotating planets perhaps)? does it have a magnetic field? and so on. youd send the probes to the ones which have the most positive results, and not the iffy star systems. that does not mean that any of those had life, or that anything that seemed unlikely would have plenty. its just you want to look at all your options and pick the best one.

Cart before the horse. We should have checked out both Mars and Europa properly by then. By which point we'd have a much better understanding of exactly where is the best place to find life.

Bear in mind that the possibility exists that Earth-type planets could actually be less likely to have life than cold worlds like Europa. The warmth could make it more likely that self-replicating molecules would be broken down before they could form. It could just as easily mean the opposite.

The point is that it's ridiculously premature to go on about habitable zones being the best place to look for life since our data set on what makes a planet likely consists of one point.

we do need more data, its true. but if we find alien germs on mars and alien fishies on europa, its still not that much data to go on. we may have to expand the habitable zone and include moon systems of large gas giants. still mars isnt exactly teeming with life, and we need more data on europa. but as it stands the habitable zone has the highest probability. we need to discover life elsewhere before we can improve upon the known the planetary requirements for life. if we had the technology today to send a probe to a star system like the one discussed in this thread, we would look for a system with a planet much like our own.

There's also the question of adapting the planet for our exploitation. We'll be introducing Earth people, things, and problems to the new planet and, in turn, will have alien factors introduced to ourselves. Nuking the planet and starting over is one rather shoddy method. To eviscerate the planet of all forms of life as well as viruses would be virtually impossible to do though perhaps easier to recover from.

[Grizzly]

Also interesting is that it is very probably tidally locked with the star (like the moon is with the earth), meaning it has one side which is perpetually in daylight, while the other side is in perpetual night.  This implies a scorching hot dayside, a frozen cold nightside, and a region in between where the temperature is just right to maintain liquid water and possibly even life.  Would make a great setting for a sci-fi, wouldn't it?

The Star Wars mUltiverse has such a planet .

[Turambar]

Wouldn't it be extremely windy along the terminator?

[watsisname]

Also interesting is that it is very probably tidally locked with the star (like the moon is with the earth), meaning it has one side which is perpetually in daylight, while the other side is in perpetual night.  This implies a scorching hot dayside, a frozen cold nightside, and a region in between where the temperature is just right to maintain liquid water and possibly even life.  Would make a great setting for a sci-fi, wouldn't it?

The Star Wars mUltiverse has such a planet .

So does Metroid, actually.

[Bob-san]

Wouldn't it be extremely windy along the terminator?

It would depend on the atmospheric model. I'd assume no since there'd be few global wind currents: the sun-facing side would be high-pressure while the dark side would be low-pressure. In addition, the far side would likely have much more solid or liquid water.

[watsisname]

Mmm, interesting.  From a study in 2003:

M stars constitute 75% of main sequence stars though, until recently, their star systems have not been considered suitable places for habitable planets to exist. In this study the climate of a synchronously rotating planet around an M dwarf star is evaluated using a three-dimensional global atmospheric circulation model. The presence of clouds and evaporative cooling at the surface of the planet result in a cooler surface temperature at the subsolar point. Water ice forms at the polar regions and on the dark side, where the minimum temperature lies between -30°C and 0°C. As expected, rainfall is extremely high on the starlit side and extremely low on the dark side. The presence of a dry continent causes higher temperatures on the dayside, and allows accumulation of snow on the nightside. The absence of any oceans leads to higher day-night temperature differences, consistent with previous work. The present study reinforces recent conclusions that synchronously rotating planets within the circumstellar habitable zones of M dwarf stars should be habitable, and therefore M dwarf systems should not be excluded in future searches for exoplanets.

Doesn't say much about surface winds, unfortunately, but I think I'd agree that there would be a strong flow of wind across the terminator.  The cooler temperatures at the subsolar point was surprising though.

[Bobboau]

if I was trying to determine which planet to visit I think I would care less about the position it had in the system and more about the composition of it's atmosphere, and I would not hold water as vital.

[FUBAR-BDHR]

Yea we can create the water supply as we drink the shipments of beer.