Formation of the moon brought water to Earth

https://phys.org/news/2019-05-formation-moon-brought-earth.html

by dnetesn • 7 years ago

82 25 7 years ago

wait what?

simonh3• 7 years ago

All the other inner planets and asteroids are dry, but Earth is wet, so it’s always been a bit of a mystery where the water came from.

encoderer• 7 years ago

Where did the water on Mars come from? Any correlation?

mirimir• 7 years ago

So is Theia's core now Mercury?

dr_orpheus• 7 years ago

The theory is that much of Theia was absorbed in to the Earth and the mass that was ejected during the collision became the moon.

https://en.wikipedia.org/wiki/Theia_(planet)

RosanaAnaDana3• 7 years ago

I don't know if there are any astrobiologists or chemists, but this brings to mind one of my favorite pet theories regarding abiogenesis, one that I've been thinking of more and more since the new horizons mission.

When we did the flyby of Pluto, I was drop jawed when we saw how dynamic the surface was. I sincerely expected a rockier, more oxidized, surface with no clear evidence of a geological cycle. Obviously what we saw was far more complex, and it brought the idea that a geology of volatile ices would be possible on these more marginal bodies (like Pluto).

The question I have is regarding what kinds of chemistry are possible on icy bodies like Pluto. If there is a complex geology, this indicates to me that things are going from liquid to solid (nitrogen ice, oxygen ice, etc..), so are some kinds of chemical bonds (specifically, organic ones) can form if a body like Pluto is has a dynamic geology?

Is it possible that the organic precursors for life are constantly accumulating on icy bodies like Pluto, and while obviously, live can't form on Pluto, could an impact discharge a massive quantity of precursor chemistry onto a planet more hospitable?

Its an interesting aside that pretty much imminently after the earths surface solidified and cooled after the impact even, life began.

dumbfoundded4• 7 years ago

Not an expert here at all but asteroids often do carry precursors for life.

Asteroids on Earth have been found carrying organic compounds: https://www.smithsonianmag.com/science-nature/the-building-b...

RosanaAnaDana3• 7 years ago

Sure, but my point here isn't about presence, but quantity. We've known that radiation can cause the creation of bio-molecules and precursor molecules for a very long time. But there almost no way that process can generate a significant enough quantity of these molecules to really seed planets. Largely its about concentration gradients, which is why I personal have found arguments about life forming via early oceans unconvincing. A couple asteroids (or even hundreds) worth of bio-molecules spread out over an ocean, is still basically nothing. You have to have enough material concentrated in a small enough space; you need a thermodynamic process that postpones equilibrium; then you need a gradient to drive the formation of more and more complicated molecules.

Like, Pluto type objects are far and away more common then earthlike objects. If there is a process that can accumulate bio-molecules in mass on these types of bodies, that's pretty game changing.

photojosh2• 7 years ago

You've probably read 'The Vital Question'? [0] I thoroughly enjoyed it and the theory presented that life originated on alkaline marine vents where there were natural energy gradients that could be exploited.

Its an interesting aside that pretty much imminently after the earths surface solidified and cooled after the impact even, life began.

So when I read this, it makes me want to read more about how these conditions could have been set up. Can you point me towards a good read(s) on this pre-life stage of Earth?

[0] https://www.goodreads.com/book/show/26530386-the-vital-quest...

RosanaAnaDana3• 7 years ago

No I've not read that. My background is in botany and I took coursework in evolutionary biology and evolutionary theory. Its much more technical than the book you referenced, but I highly recommend:

https://www.amazon.com/Not-Design-Retiring-Darwins-Watchmake...

Warning: this book is very much oriented towards a technical discussion in evolutionary biology. Its not really built for entertainment.

kristianp• 7 years ago

That doesn't bode well for the idea of habitable planets in other solar systems. If this kind of collision is relatively rare, most rocky exo-planets will have much less water than Earth has.

Reminds me of Asimov's storyline in the Foundation series about the rarity of the planet that humans come from (and the reason no complex lifeforms existed anywhere else), although his premise was a large amount of radioactivity on earth, IIRC.

dumbfoundded4• 7 years ago

We just don't know enough about life or planet formation to know how this bodes.

On its surface, everything that makes the formation of the Earth appear rarer would suggest life, in general, is rarer but honestly we don't know. We don't even know if there's life on Europa even though there would appear to be all the conditions present to make life as it lives at the bottom of our oceans.

We don't even know if water is a reasonable prerequisite for life. We don't know if life has to be carbon-based. Sulfur also presents a reasonable alternative. Would we even recognize other life if was right in front of us if it relied on completely different mechanisms? Maybe even our idea of time is too short lived or long lived to even recognize other complex systems as alive.

We shouldn't extrapolate too much from a single data point.

ianai• 7 years ago

I’m glad I’m not the only one thinking that! All of the paradoxes and stuff just strike me as hubris, at best.

raz32dust• 7 years ago

+1. Also, we don't have many data points to suggest that this is relatively rare that objects from outer solar systems tend to move in later. May be that is quite common, we don't really know - we don't have enough data.

And even if we assume it is rare, how rare exactly? The numbers are so uncertain that we can say nothing yet.

raducu2• 7 years ago

Genuinely curious about sulfur-based life, what indications do we have that it could actually form the base for life instead of carbon?

I mean I know very little about biochemistry but I do know life on earth has some INCREDIBLY complex biochemistry based on carbon.

Also what's the point of sulfur-based life, isn't carbon omnipresent in the universe?

Why wouldn't liquid water be an absolute must for life? Wouldn't any kind of complex life need a solvent that would allow the complex biochemistry to take place? What would the alternatives to water then be?

simonh3• 7 years ago

It simply isn't true that we're completely ignorant on these questions. We know an awful lot about the chemistry of all the known elements and it's pretty clear water and Carbon are by far the best candidates for supporting complex, rich chemistries across a wide range of environmental conditions.

It's not that alternative life chemistries are necessarily impossible, but equally it's plausible that they might well be non-viable above a very primitive level at best. They would have many orders of magnitude fewer options available to them for biochemical resources, pathways and molecular geometries to take advantage of. Chemically speaking, not all elements are created equal.

Take Sulphur for example. It's far more reactive than carbon, so chemically unstable in many more environmental conditions. It generally only forms linear chains, rather than the complex branching structures of carbon. It also bonds with far fewer other elements in ways that are likely to be chemically useful. If you have carbon available, Sulphur is a very poor substitute. It's high reactivity might make it a passable alternative to Oxygen though.

burlesona• 7 years ago

As the sibling comment points out, we really just don't know what else is out there and how common or rare the earth situation is.

I think the way one reacts to something like this is an interesting Rorschach test, though.

I had the same gut reaction you do: this probably means that life-bearing planets are even rarer than I already thought. But I think that because it confirms my personal bias - that we don't see evidence of other life in the galaxy because it isn't there.

Other replies to your comment call this hubris and remind you that you're extrapolating - which is true. But in my experience with people who jump that direction, it's because their bias (and/or hope) is that we can't be alone and that we just haven't found other life yet.

I just think that's interesting.

njarboe• 7 years ago

The scientific article that this summary is based on can be found here[1].

[1]http://dx.doi.org/10.1038/s41550-019-0779-y

vertline3• 7 years ago

I was just reading that Mars was found to have the remains of an icecap one mile under the surface, so was Mars also hit with a meteor?

tigerlily• 7 years ago

What would happen if we added (5 or 10%) more water to the Earth today?

Formation of the moon brought water to Earth

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