in Vernor Vinge's novel A Deepness in the Sky the alien planet freezes for part of the year and the intelligent aliens have evolved to survive being frozen and thawed. One group develops technology to say unfrozen while their enemies are frozen and this gives them a huge advantage.
Great book and I highly recommend it. Also has concepts of realistic mind control that is VERY creepy and the ultimate in distributed computing based on smart dust.
The habitable zone is defined as the area around a star where liquid water could be found, there is no "our" habitable zone and "their" habitable zone.
The terminology was probably chosen specifically to be somewhat clickbait, so it's probably not worth picking apart the words "habitable zone".
The core idea really boils (heh) down to water, _i.e._ the "universal solvent". You can certainly argue that liquid water may not be necessary for life, but it's hard to argue that water's presence isn't a decent prior for potential life.
But directly detecting liquid water in extrasolar planets is _hard_. So we do the next best thing and try to use whatever indirect signals we got. We know that liquid water can only exist within some range of temperatures and pressures. So let's just start with temperature.
What things can affect the surface temperature of a planet? Amount of energy received from the parent star (i.e. stellar irradiance), geothermal heating, tidal forces between a moon and planet, and probably many others. Stellar energy stands out as being the biggest contributor of energy and, fortunately, the easiest one to measure.
Of course, you could have localized sources of favorable conditions, like thermal vents or whatever, but those kinds of things are _way_ beyond our ability to detect with current tech.
So, we've narrowed down our focus to _one big contributing factor for potential life_, the amount of energy received from a planet's host star. But how can we relate energy to temperature? This is effectively where all the physics and astronomy come in via thermodynamics, orbital mechanics, and stellar physics.
Suffice it to say that all the effects combine to give a range of possible orbital radii and planet sizes where liquid water has a good chance of existing on the planteary surface.
This range of radii and planet sizes is the concept that matters. The name for this idea is "habitable zone", which suggests why we might care, compared to the more precise "orbital and planetary mass parameters favorable to liquid water formation at average planetary surface".
This kind of resource variability seems likely to favor the development of intelligence, so there’s that.
But I m sure we will find that the planet has issues that make complex life unlikely, just on a statistical basis.
Simple life seems increasingly likely to propagate through panspermia, based on what we find deep inside the crust of our planet. Life forms that feed off of radioactive decay especially seem promising for panspermia.
I wouldn’t be surprised at all if we discovered that for habitable zone, earth-like planets , the presence of simple life forms deep inside the crust turns out to be the rule rather than the exception, at least in our corner of the galaxy.
> Its distance from its star changes significantly, causing the planet to move from the outer edge of the habitable zone to the inner edge throughout its year
UltraSane|1 year ago
Great book and I highly recommend it. Also has concepts of realistic mind control that is VERY creepy and the ultimate in distributed computing based on smart dust.
ZYbCRq22HbJ2y7|1 year ago
UncleOxidant|1 year ago
dmix|1 year ago
ceejayoz|1 year ago
Life on such a planet seems likely to hibernate just like some Earth life already does.
doctoboggan|1 year ago
The habitable zone is defined as the area around a star where liquid water could be found, there is no "our" habitable zone and "their" habitable zone.
xelxebar|1 year ago
The core idea really boils (heh) down to water, _i.e._ the "universal solvent". You can certainly argue that liquid water may not be necessary for life, but it's hard to argue that water's presence isn't a decent prior for potential life.
But directly detecting liquid water in extrasolar planets is _hard_. So we do the next best thing and try to use whatever indirect signals we got. We know that liquid water can only exist within some range of temperatures and pressures. So let's just start with temperature.
What things can affect the surface temperature of a planet? Amount of energy received from the parent star (i.e. stellar irradiance), geothermal heating, tidal forces between a moon and planet, and probably many others. Stellar energy stands out as being the biggest contributor of energy and, fortunately, the easiest one to measure.
Of course, you could have localized sources of favorable conditions, like thermal vents or whatever, but those kinds of things are _way_ beyond our ability to detect with current tech.
So, we've narrowed down our focus to _one big contributing factor for potential life_, the amount of energy received from a planet's host star. But how can we relate energy to temperature? This is effectively where all the physics and astronomy come in via thermodynamics, orbital mechanics, and stellar physics.
Suffice it to say that all the effects combine to give a range of possible orbital radii and planet sizes where liquid water has a good chance of existing on the planteary surface.
This range of radii and planet sizes is the concept that matters. The name for this idea is "habitable zone", which suggests why we might care, compared to the more precise "orbital and planetary mass parameters favorable to liquid water formation at average planetary surface".
nirav72|1 year ago
K0balt|1 year ago
But I m sure we will find that the planet has issues that make complex life unlikely, just on a statistical basis.
Simple life seems increasingly likely to propagate through panspermia, based on what we find deep inside the crust of our planet. Life forms that feed off of radioactive decay especially seem promising for panspermia.
I wouldn’t be surprised at all if we discovered that for habitable zone, earth-like planets , the presence of simple life forms deep inside the crust turns out to be the rule rather than the exception, at least in our corner of the galaxy.
pmontra|1 year ago
Too bad that the year is relatively short. If it were hundreds of Earth years that could be like Helliconia https://en.m.wikipedia.org/wiki/Helliconia