9

While this does not directly answer the question, these two ideas are relevant: Rare Earth hypothesis and Mediocrity principle. More focused to the question, This letter to nature discusses the purposed link between evolution/mutation rate during of life and magnetic pole reversal periods. You see, when the magnetic fields reversed, it widely thought that ...


7

As far as I know there are no extinction phases that have been connected to a magnetic reversal. From this one can argue that there is no or only minor changes in the amount of radiation that reaches the Earth's surface. Life in the oceans and underwater anyway has an extra protective layer, i.e. water (but also see this as a grain of salt because most ...


4

can we say that a water-world does not have plate tectonics? No we can't. Take for example Earth, add in a lot of water to cover all of the continents and you get a water-world with active plate tectonics. The driver for plate tectonics is not whether water exist or not on the surface, but rather the internal heat a planet contains. Or, the plates of plate ...


4

I'm basing this answer off an article: Kevin Lepot, Karim Benzerara, Gordon E. Brown Jr., Pascal Philippot (2008). 'Microbially influenced formation of 2.7 billion-year-old stromatolites'. Nature Geoscience Vol.1 No.2, pp.118–121. DOI: http://dx.doi.org/10.1038/ngeo107 Instruments that are desirable (and are actually used) to study stromatolites/freshwater ...


3

From what I've read so far, it appears jarosite may not be a prerequisite for the formation of certain life forms, instead that it is produced by certain organisms. Río Tinto (Huelva, southwestern Spain) is an extreme environment with a remarkably constant acidic pH and a high concentration of heavy metals, conditions generated by the metabolic activity ...


3

Analogues to Mars Recurring Slope Linea (RSL) is a current study topic in Antarctica (Dry Valleys). On Earth, analogues are known as water tracks, which are linear zones of higher moisture along slopes in polar regions where water transit during snowmelt. This figure from Ward Hunt Island (NU, Canada) show well developed and typical water tracks. Source: ...


3

I'm by no means an expert, but this Wikipedia link suggests that oceans make plate tectonics more likely, not less likely: https://en.wikipedia.org/wiki/Plate_tectonics#Exoplanets So, a planet with twice the surface water as earth, covered by oceans might have almost no land but I think it's unlikely oceans would stop plate tectonics cause the heat still ...


2

It would be impossible to answer this definitively, of course, but I would have to hypothesize that a water-world could harbor life, not intelligent, tool-using life, but basic stuff. Here's my logic: planet accretion leaves behind a lot of heat, even if it's not from radioactivity. Just the kinetic energy from accretion would take (probably) a billion years ...


2

You can just think of this in terms of energy. To leave a mark in the geologic record, you have to use something that is at least as strong as the forces that are shaping the world around you: erosion, melting, tectonic forces, wind and weather. These are all very energetic things that are happening around us all the time, and for long time spans. If you ...


2

No, it is not possible. The only thing I could think about is re/de/magnetisation of magnetic minerals. Even then I'm not sure it's feasible, because you to form a magnetic field you need an electric current in motion, but that's a question for physics, not here. So far, the major magnetic signals recorded in the geological history are well understood. ...


2

Note: As I discovered after writing most of this answer, this question on Space Stack Exchange is closely related, and called2voyage’s answer uses some of the same early points that I do, as it discusses the paper you referenced. It’s worth noting that the results of McKay & Smith were purely theoretical, and their paper was originally received by the ...


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