5 ms·

> It's not in our habitable zone. The habitable zone is defined as the area around a star where liquid water could be found, there is no "our" habitable zone a

> It's not in our habitable zone. 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.

ceejayoz 2y ago
Parts of our own Earth aren't in the habitable zone, by that definition. Even here we get big surprises - undersea vents were unexpected oases, microbes miles deep underground, microbes living in boiling water in Yellowstone... Not all life in the universe may require liquid water, nor require it 24/7. In our own solar system, some planetoids outside our supposed habitable zone likely have some liquid water - Europa and Enceladus, for example.
- patmorgan23 2y ago
  Do any of those zones actually have life? The two examples you gave... Include liquid water. As far as I know there is no life native to the coldest parts of the earth that have no liquid water. It is entirely possible there is some other form of life that does not require liquid water, but we have yet to discover it.
  - ceejayoz 2y ago
    > The two examples you gave... Include liquid water. This specific planet spends half its orbit in said zone. Here on Earth, we have creatures like https://en.wikipedia.org/wiki/Mudskipper https://en.wikipedia.org/wiki/Mudskipper that can survive severe dry spells, and fish that can happily freeze sold in ice for months. Europa spends zero time in our solar system's "habitable zone", but because of its conditions, may still possess large amounts of liquid water. It's a perfect example of why the "zone" may be overly narrowly defined, even for Earth-like water-dependent life. > It is entirely possible there is some other form of life that does not require liquid water, but we have yet to discover it. And we certainly won't if we only look in Earth-defined "habitable" zones.
- dylan604 2y ago
  You seem to be deliberately trying to pervert the definition of habitable zone. Just because there are regions on a planet in the habitable zone that contains ice does not mean it is not in the habitable zone. If it were further out beyond the habitable zone, there would be no liquid water at the surface. To quote my friend Andy Dufresne, "How can you be so obtuse?...Is it deliberate?"
  - ceejayoz 2y ago
    > You seem to be deliberately trying to pervert the definition of habitable zone. No, I'm saying an Earth-life centric metric is a bit of an odd choice when evaluating extrasolar planets. It's like an African elephant declaring Norway uninhabitable.
    - pc86 2y ago
      Earth is the only environment in which we've found life, so it makes sense to first focus on other Earth-like planets. Your point is not without merit but taken to the extreme it would be like sending exploratory teams to the Mariana Trench to look for un-contacted human tribes. We have incontrovertible evidence that water + carbon + time sometimes equals life. We have no evidence of any other non-carbon or non-water chemistries resulting in life so why wouldn't we focus on locations potentially rich in water and carbon first?
      - ceejayoz 2y ago
        The first exoplanet detection was in 1992; in my lifetime, "there are no planets outside our solar system" was roughly as supportable as "there is no life outside our solar system" is today. Here on Earth, we can barely decide if viruses are life or not, and discover new things within our own bodies pretty regularly, despite... a lot of direct access to them. (Example: https://www.science.org/content/article/it-s-insane-new-viruslike-entities-found-human-gut-microbes https://www.science.org/content/article/it-s-insane-new-viru...) We should be casting a pretty wide net.
        2y ago
- throwup238 2y ago
  > Parts of our own Earth aren't in the habitable zone, by that definition. What parts would that be? Even the polar caps have huge liquid water oceans underneath. Unless you’re talking about the mantle or molten core, there are no uninhabitable areas on earth as per astrobiology (not even miles underground). > Not all life in the universe may require liquid water, nor require it 24/7. You might as well be talking about leprechauns and unicorns and Horta. Water is the universal solvent and has at least five unique properties that are as critical to life as carbon’s ability to form four chemical bonds. You’re correct that moons experiencing tidal heating can contain liquid water, but that’s irrelevant to a planet. The habitable zone is specifically talking about planets (rocky ones at that), not any arbitrary satellite. It’s a term of art in astronomy, not a colloquialism.
  - ceejayoz 2y ago
    > Unless you’re talking about the mantle or molten core, there are no uninhabitable areas on earth as per astrobiology (not even miles underground). We've found microbes that can survive at 120 Celsius, -25 Celsius, very high and very low pH, large amounts of ionizing radiation, intense pressures, etc. Habitability is a wide range encompasing scenarios not conducive to liquid water. > Water is the universal solvent and has at least five unique properties that are as critical to life as carbon’s ability to form four chemical bonds. None of that rules out life on other chemistries. It makes water+carbon-based life the most likely scenario on planets with liquid water, but hardly rules out other potential biologies. > You’re correct that moons experiencing tidal heating can contain liquid water, but that’s irrelevant to a planet. The habitable zone is specifically talking about planets (rocky ones at that), not any arbitrary satellite. But we should absolutely be looking at planet-sized moons with potentially habitable conditions, which we believe to be quite common. They are, after all, more common than the single "habitable zone" planet even within our own system.
    - throwup238 2y ago
      Dude, just read the Wikipedia article: https://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry#Non-water_solvents https://en.wikipedia.org/wiki/Hypothetical_types_of_biochemi... It’s not impossible, but we’ve got a ton of evidence why it’s extremely unlikely. It’s a long list including stuff like possible quantum transition states enabling biochemistry, reactivity with oxygen (the third most abundant element), and spectroscopic transparency. It’s an active area of research that keeps coming up with dead ends. Ammonia and methane are the best candidates but those would only be possible at low temperatures that preclude lots of other reactions.
connorgutman 2y ago
Regardless of the official definition, the word “habitable” is highly subjective. Extremophiles like tardigrades can survive being frozen and/or completely dehydrated. A planet with an eccentric orbit like this one could hypothetically support species capable of entering some form of extreme hibernation during part of their year.
- hajola 2y ago
  While it's possible for conditions for life to emerge or sustain itself to be present beyond the habitable zone (e.g. there's likely a subsurface ocean orbiting the farthest plant from the Sun on Triton), afawk it is more probable that life forms in the habitable zone. That is the only one we have a data point for.
  - ceejayoz 2y ago
    A sample size of one tells us it it possible, but nothing about what’s most likely.
    - hajola 2y ago
      Well, we also know where we haven't found signs of life. So from that perspective we have more data.
- glenstein 2y ago
  >Regardless of the official definition, the word “habitable” is highly subjective Well, one constructive way to take it out of the realm of subjectivity is to put forward a specific definition.
- ziddoap 2y ago
  >the word “habitable” is highly subjective. Sure, but not in the context of "habitable zone" which is a specific term of art in astrobiology.
  - ceejayoz 2y ago
steve_adams_86 2y ago
Given the mass of the planet, if there's a lot of water it's entirely possible there could be oceans which stay warm due to a hot core.

> It's not in our habitable zone. 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.

ceejayoz 2y ago

Parts of our own Earth aren't in the habitable zone, by that definition. Even here we get big surprises - undersea vents were unexpected oases, microbes miles deep underground, microbes living in boiling water in Yellowstone... Not all life in the universe may require liquid water, nor require it 24/7. In our own solar system, some planetoids outside our supposed habitable zone likely have some liquid water - Europa and Enceladus, for example.

patmorgan23 2y ago
Do any of those zones actually have life? The two examples you gave... Include liquid water. As far as I know there is no life native to the coldest parts of the earth that have no liquid water. It is entirely possible there is some other form of life that does not require liquid water, but we have yet to discover it.
- ceejayoz 2y ago
  > The two examples you gave... Include liquid water. This specific planet spends half its orbit in said zone. Here on Earth, we have creatures like https://en.wikipedia.org/wiki/Mudskipper https://en.wikipedia.org/wiki/Mudskipper that can survive severe dry spells, and fish that can happily freeze sold in ice for months. Europa spends zero time in our solar system's "habitable zone", but because of its conditions, may still possess large amounts of liquid water. It's a perfect example of why the "zone" may be overly narrowly defined, even for Earth-like water-dependent life. > It is entirely possible there is some other form of life that does not require liquid water, but we have yet to discover it. And we certainly won't if we only look in Earth-defined "habitable" zones.
dylan604 2y ago
You seem to be deliberately trying to pervert the definition of habitable zone. Just because there are regions on a planet in the habitable zone that contains ice does not mean it is not in the habitable zone. If it were further out beyond the habitable zone, there would be no liquid water at the surface. To quote my friend Andy Dufresne, "How can you be so obtuse?...Is it deliberate?"
- ceejayoz 2y ago
  > You seem to be deliberately trying to pervert the definition of habitable zone. No, I'm saying an Earth-life centric metric is a bit of an odd choice when evaluating extrasolar planets. It's like an African elephant declaring Norway uninhabitable.
  - pc86 2y ago
    Earth is the only environment in which we've found life, so it makes sense to first focus on other Earth-like planets. Your point is not without merit but taken to the extreme it would be like sending exploratory teams to the Mariana Trench to look for un-contacted human tribes. We have incontrovertible evidence that water + carbon + time sometimes equals life. We have no evidence of any other non-carbon or non-water chemistries resulting in life so why wouldn't we focus on locations potentially rich in water and carbon first?
    - ceejayoz 2y ago
      The first exoplanet detection was in 1992; in my lifetime, "there are no planets outside our solar system" was roughly as supportable as "there is no life outside our solar system" is today. Here on Earth, we can barely decide if viruses are life or not, and discover new things within our own bodies pretty regularly, despite... a lot of direct access to them. (Example: https://www.science.org/content/article/it-s-insane-new-viruslike-entities-found-human-gut-microbes https://www.science.org/content/article/it-s-insane-new-viru...) We should be casting a pretty wide net.
      - 2y ago
throwup238 2y ago
> Parts of our own Earth aren't in the habitable zone, by that definition. What parts would that be? Even the polar caps have huge liquid water oceans underneath. Unless you’re talking about the mantle or molten core, there are no uninhabitable areas on earth as per astrobiology (not even miles underground). > Not all life in the universe may require liquid water, nor require it 24/7. You might as well be talking about leprechauns and unicorns and Horta. Water is the universal solvent and has at least five unique properties that are as critical to life as carbon’s ability to form four chemical bonds. You’re correct that moons experiencing tidal heating can contain liquid water, but that’s irrelevant to a planet. The habitable zone is specifically talking about planets (rocky ones at that), not any arbitrary satellite. It’s a term of art in astronomy, not a colloquialism.
- ceejayoz 2y ago
  > Unless you’re talking about the mantle or molten core, there are no uninhabitable areas on earth as per astrobiology (not even miles underground). We've found microbes that can survive at 120 Celsius, -25 Celsius, very high and very low pH, large amounts of ionizing radiation, intense pressures, etc. Habitability is a wide range encompasing scenarios not conducive to liquid water. > Water is the universal solvent and has at least five unique properties that are as critical to life as carbon’s ability to form four chemical bonds. None of that rules out life on other chemistries. It makes water+carbon-based life the most likely scenario on planets with liquid water, but hardly rules out other potential biologies. > You’re correct that moons experiencing tidal heating can contain liquid water, but that’s irrelevant to a planet. The habitable zone is specifically talking about planets (rocky ones at that), not any arbitrary satellite. But we should absolutely be looking at planet-sized moons with potentially habitable conditions, which we believe to be quite common. They are, after all, more common than the single "habitable zone" planet even within our own system.
  - throwup238 2y ago
    Dude, just read the Wikipedia article: https://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry#Non-water_solvents https://en.wikipedia.org/wiki/Hypothetical_types_of_biochemi... It’s not impossible, but we’ve got a ton of evidence why it’s extremely unlikely. It’s a long list including stuff like possible quantum transition states enabling biochemistry, reactivity with oxygen (the third most abundant element), and spectroscopic transparency. It’s an active area of research that keeps coming up with dead ends. Ammonia and methane are the best candidates but those would only be possible at low temperatures that preclude lots of other reactions.

connorgutman 2y ago

Regardless of the official definition, the word “habitable” is highly subjective. Extremophiles like tardigrades can survive being frozen and/or completely dehydrated. A planet with an eccentric orbit like this one could hypothetically support species capable of entering some form of extreme hibernation during part of their year.

hajola 2y ago
While it's possible for conditions for life to emerge or sustain itself to be present beyond the habitable zone (e.g. there's likely a subsurface ocean orbiting the farthest plant from the Sun on Triton), afawk it is more probable that life forms in the habitable zone. That is the only one we have a data point for.
- ceejayoz 2y ago
  A sample size of one tells us it it possible, but nothing about what’s most likely.
  - hajola 2y ago
    Well, we also know where we haven't found signs of life. So from that perspective we have more data.
glenstein 2y ago
>Regardless of the official definition, the word “habitable” is highly subjective Well, one constructive way to take it out of the realm of subjectivity is to put forward a specific definition.
ziddoap 2y ago
>the word “habitable” is highly subjective. Sure, but not in the context of "habitable zone" which is a specific term of art in astrobiology.
- ceejayoz 2y ago

steve_adams_86 2y ago

Given the mass of the planet, if there's a lot of water it's entirely possible there could be oceans which stay warm due to a hot core.