MagnaCool--Habitable Exoplanet!

[KrazyHorse]

Originally posted by Dauphin


Given the spread in temperatures 0-40C that may be true with only a few assumptions, but a 'straightforward' exercise in thermodynamics is not so straightforward if it has an atmosphere like Venus, say. Do a straightforward analysis assuming a nitrogen atmosphere when it's actually CO2 and it will be wrong. Won't it?

It will be, but the spread of temps is actually broad enough to cover the large majority of available parameter space.

0C is probably with virtually 0 greenhouse effect, while 40C is with a pretty significant effect.

If it's got an atmosphere like Venus, then of course all bets are off. But there are good reasons to believe that Venus is fairly unusual...

[Arrian]

There are tons of things that could make the thing uninhabitable, between the gs, the atmosphere ("sorta like Earth" doesn't really cut it), possible native life against which we have no defenses (diseases), etc.

But it's still cool.

-Arrian

[Dauphin]

Originally posted by KrazyHorse


It will be, but the spread of temps is actually broad enough to cover the large majority of available parameter space.

0C is probably with virtually 0 greenhouse effect, while 40C is with a pretty significant effect.

If it's got an atmosphere like Venus, then of course all bets are off. But there are good reasons to believe that Venus is fairly unusual...

I'm sure the figures were chosen, in part, under what if scenarios and that 0C and 40C are the extremities of 90% confidence level or somesuch. There is another part of me that thinks the figures 0C to 40C are touted as it's familiar to the masses and a higher confidence range of -10 to 55C would paint a more unfamiliar scenario. I'm not implying dishonesty in the science or the ignoring other possible results, only that there is a human bias towards nice numbers for press releases.


There is also the issue that it's the mean temperature. If you ask people what they think a good mean temperature for the Earth would be, I would guess that they overestimate and end up saying what they want the local weather to be instead.

[KrazyHorse]

I agree.

[Ned]

Question:

How many here would send a manned mission to such a planet as soon as feasible without having first sent an unmanned mission to explore and report back? I suspect, 0.

So the question is, how soon can we launch an unmanned mission? We already can build ships that can exit the solar system. We should be able to build ships that can reach such a planet "in time," perhaps in just a few thousand years.

Should we do it as soon as we can?

And, given our current technology, just how long would it take to drop or accellerate (I don't know which direction the planet in question is" a ship in the right direction. The physical journey will be a lot longer, I believe, than 20 light years.

[Berzerker]

did the article say the planet was tidally locked? wouldn't that mean a hot and cold side?

[Geronimo]

[QUOTE] Originally posted by KrazyHorse

[edit... how did I miss Dauphins post? ]

[Geronimo]

Originally posted by KrazyHorse

If it's got an atmosphere like Venus, then of course all bets are off. But there are good reasons to believe that Venus is fairly unusual...

How long has it been recognized that Venus is unusual? I'm surprised we have any handle at all at this point on what's usual or unusual when it comes to extrasolar planetary systems.

[Dauphin]

Originally posted by Berzerker
did the article say the planet was tidally locked? wouldn't that mean a hot and cold side?

Depends on how good the heat dissipation is due to atmospheric or oceanic currents.

[Berzerker]

cant be too good, Venus maintains comparable temps because of its thick atmosphere. If they have a temp estimate for this planet they got one side, night or day...

How long has it been recognized that Venus is unusual? I'm surprised we have any handle at all at this point on what's usual or unusual when it comes to extrasolar planetary systems.

First clue was its "spin", a Venusian day is longer than its year and it rotates clockwise (retrograde) v-e-r-y s-l-o-w-l-y. The planet is upside down, no magnetic field for protection, and it doesn't spin. Which is why I had to laugh when a JPL spokesman on LA radio claimed we had to send a probe to Venus for study so we can prevent the same thing happening to our atmosphere.

[KrazyHorse]

Originally posted by Ned
And, given our current technology, just how long would it take to drop or accellerate (I don't know which direction the planet in question is" a ship in the right direction. The physical journey will be a lot longer, I believe, than 20 light years.

I have no idea what you're saying.

[Geronimo]

Originally posted by Berzerker
cant be too good, Venus maintains comparable temps because of its thick atmosphere. If they have a temp estimate for this planet they got one side, night or day...



First clue was its "spin", a Venusian day is longer than its year and it rotates clockwise (retrograde) v-e-r-y s-l-o-w-l-y. The planet is upside down, no magnetic field for protection, and it doesn't spin. Which is why I had to laugh when a JPL spokesman on LA radio claimed we had to send a probe to Venus for study so we can prevent the same thing happening to our atmosphere.

yes yes, old news. But how do we know this condition is unusual elsewhere? We have at least two planets in our solar system with curious rotation, Uranus and Venus.

[Berzerker]

I think he's talking about a ship moving toward or away from the galactic center

[Geronimo]

Originally posted by Berzerker
I think he's talking about a ship moving toward or away from the galactic center

I figured his question had something to do with how much of the journey would be at cruising speed and how much would be spent accelerating and decelerating.

[Berzerker]

yes yes, old news. But how do we know this condition is unusual elsewhere? We have at least two planets in our solar system with curious rotation, Uranus and Venus.

We also have evidence of a bombardment around or shortly after 4 bya, so "usual" would mean planets that haven't been plastered by asteroids a 1/2 billion years after they formed. And you asked for old news

How long has it been recognized that Venus is unusual?

See