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Phosphine was detected in Saturn's atmosphere at the Caltech Submillimeter Observatory (right next to the JCMT) decades ago (http://www.ericweisstein.com/resear

Phosphine was detected in Saturn's atmosphere at the Caltech Submillimeter Observatory (right next to the JCMT) decades ago (http://www.ericweisstein.com/research/papers/dps93/ http://www.ericweisstein.com/research/papers/dps93/). I don't recall anyone screaming "Life on Saturn" back then. I think this is being overhyped.

ncallaway 6y ago
From the other thread about this, people were saying there are known abiotic chemical pathways to generate Phosphine on gas giants, so detection of Phosphine on Saturn and Jupiter is much less interesting. Apparently those know pathways don't work on rocky planets, which is why a detection on Venus is more interesting than a detection on Saturn. I still expect the outcome to eventually be: "we have found a new pathway to Phosphine, that's consistent with a rocky planet", but it definitely seems like a discovery that warrants attention and further study.
- Robotbeat 6y ago
  I have often thought of Venus as halfway between a gas giant and a rocky planet.
  - sedatk 6y ago
    Why?
    - Robotbeat 6y ago
      Because like a gas giant, the surface is effectively unreachable or at least absolutely uninhabitable (if it even exists for a gas giant). The atmosphere of Venus, like a gas giant, becomes a very hot, supercritical gas as you go deeper. Like a gas giant, the only potential habitable area is in the atmosphere. Venus still has a sensible surface, although it's unclear if that concept makes sense for a gas giant. "Gas dwarfs" exist, which have a thick atmosphere around a rocky planet (i.e. around Earth's mass), but Venus probably doesn't qualify for that. It's sort of a continuum, though, so the dividing line is somewhat arbitrary.
      - saberdancer 6y ago
        In an colonization sense perhaps, but the environment is very different. Pressures while high on Venus are orders of magnitudes lower than in gas giant atmospheres.
        Robotbeat 6y ago
        In a broad, habitability of life standpoint, with human settlement being a subset of that.
      - ncallaway 6y ago
        I think looking at it as a continuum makes some amount of sense, though in this case the authors of the paper seem to have done lots of due diligence in terms of doing the chemistry to check known production paths. As in, there is known chemistry that produces phosphine at the temperatures and pressures that exist on Saturn and Jupiter, but there is not known chemistry that produces phosphine at the temperatures and pressures that exist on Venus. So for this particular chemistry, the difference between "gas giant" and "rocky planet" is still a helpful one.
danparsonson 6y ago
The difference is that Saturn is a gas giant - this discovery relates to the detection of phospine on a rocky planet, which is what makes it unexpected and difficult to explain.
falseprofit 6y ago
See Figure 4 of https://iopscience.iop.org/article/10.1086/506245/pdf https://iopscience.iop.org/article/10.1086/506245/pdf "-Overview of phosphorus chemistry as a function of temperature and pressure in a solar system composition gas."

ncallaway 6y ago

From the other thread about this, people were saying there are known abiotic chemical pathways to generate Phosphine on gas giants, so detection of Phosphine on Saturn and Jupiter is much less interesting. Apparently those know pathways don't work on rocky planets, which is why a detection on Venus is more interesting than a detection on Saturn. I still expect the outcome to eventually be: "we have found a new pathway to Phosphine, that's consistent with a rocky planet", but it definitely seems like a discovery that warrants attention and further study.

Robotbeat 6y ago
I have often thought of Venus as halfway between a gas giant and a rocky planet.
- sedatk 6y ago
  Why?
  - Robotbeat 6y ago
    Because like a gas giant, the surface is effectively unreachable or at least absolutely uninhabitable (if it even exists for a gas giant). The atmosphere of Venus, like a gas giant, becomes a very hot, supercritical gas as you go deeper. Like a gas giant, the only potential habitable area is in the atmosphere. Venus still has a sensible surface, although it's unclear if that concept makes sense for a gas giant. "Gas dwarfs" exist, which have a thick atmosphere around a rocky planet (i.e. around Earth's mass), but Venus probably doesn't qualify for that. It's sort of a continuum, though, so the dividing line is somewhat arbitrary.
    - saberdancer 6y ago
      In an colonization sense perhaps, but the environment is very different. Pressures while high on Venus are orders of magnitudes lower than in gas giant atmospheres.
      - Robotbeat 6y ago
        In a broad, habitability of life standpoint, with human settlement being a subset of that.
    - ncallaway 6y ago
      I think looking at it as a continuum makes some amount of sense, though in this case the authors of the paper seem to have done lots of due diligence in terms of doing the chemistry to check known production paths. As in, there is known chemistry that produces phosphine at the temperatures and pressures that exist on Saturn and Jupiter, but there is not known chemistry that produces phosphine at the temperatures and pressures that exist on Venus. So for this particular chemistry, the difference between "gas giant" and "rocky planet" is still a helpful one.

danparsonson 6y ago

The difference is that Saturn is a gas giant - this discovery relates to the detection of phospine on a rocky planet, which is what makes it unexpected and difficult to explain.

falseprofit 6y ago

See Figure 4 of https://iopscience.iop.org/article/10.1086/506245/pdf https://iopscience.iop.org/article/10.1086/506245/pdf "-Overview of phosphorus chemistry as a function of temperature and pressure in a solar system composition gas."