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Earth May Have Kept Its Own Water Rather Than Getting It From Asteroids (sciencemag.org)

sciencehabit writes: Carl Sagan famously dubbed Earth the 'pale blue dot' for our planet's abundant water. But where this water came from—and when it arrived—has been a longstanding debate. Many scientists argue that Earth formed as a dry planet, and gained its water millions of years later through the impact of water-bearing asteroids or comets. But now, scientists say that Earth may have had water from the start, inheriting it directly from the swirling nebula that gave birth to the solar system. If true, the results suggest that water-rich planets may abound in the universe.

45 comments

  1. Re:recycling us is not new? creation never sleeps. by Anonymous Coward · · Score: 0, Troll

    What darkweb site can I buy what you're on? And for how many bitcoins?

  2. Re:God's truth wins again by Anonymous Coward · · Score: 0

    Come on sense say's it would have taken much more than 6,000 years to fill the oceans with snowballs falling from space. So-called scientists get it wrong again.

  3. Re:God's truth wins again by Anonymous Coward · · Score: 5, Insightful

    The important question isn't how, but why.

    The flying spaghetti monster gave us water so that we could boil pasta.

  4. Re:God's truth wins again by vtcodger · · Score: 0

    OTOH, Genesis also says that the stars and planets weren't created until the third day (Genesis 1:14). That doesn't jibe with the rather abundant evidence that he/she/it left laying around about the age and evolutionary course of the Universe.

    Nothing against the Genesis creation story. On the whole, it's not all that bad a fit to Astronomy, Geology, Paleontology. For a collection of what seems to be complete nonsense, try the Great Flood as described in Genesis chapters 6 thru 9.

    Let me suggest that if you wish to believe in God, that's certainly your option. But if you wish to believe that the Bible is literally true and completely accurate, you must seriously consider the notion that God was a totally incompetent copy editor who managed to bungle the task of making the description of creation, etc match the physical evidence.

    --
    You can't see ANYTHING from a car, You've got to get out of the goddamned contraption and walk...Edward Abbey
  5. confusing being a spiritual being with 'religion' by Anonymous Coward · · Score: 0

    substitution, happens all the time... grace is a state a place a person?

  6. Re:God's truth wins again by Anonymous Coward · · Score: 0

    You do not understand what you have read or its context.

    Genesis 1:6-9 ; Psalm 74:13-17

    The Judaeo-Christian creation myth is a variation on the Canaanite and Mesopotamian creation myths. (No surprise as the Jews came out of the land of Canaan and spoke a version of their language). Leviathan/Tiamat was a dragon water goddess whose body was split to form the seas and the heavens. Psalm discusses the slaying, and Genesis describes the dividing in detail.

    The Bible's description of Earth is a flat Earth with a dome-like vault (a firmament) above holding back the waters of heaven. The vault opens to let the rains out -- and, apparently, there's enough water up there to flood the entire earth as during Noah's flood.

    You cherry pick details that match what science says, then disregard those that you do not like as metaphor. What you can't explain as metaphor or confirm as matching reality, you use to rage against truths discovered through science. You simply cannot accept that your religion is a lie rooted in ancient mythology.

  7. And water may not always have been water by rossdee · · Score: 1

    Other compounds contain Hydrogen
    and the early earth had plenty of compounds with oxygen

    1. Re:And water may not always have been water by Anonymous Coward · · Score: 0

      What compounds would those be? And where are all those displaced elements in their native form, if they've all been reduced by the hydrogen?

  8. why not? by vtcodger · · Score: 2, Interesting

    Thanks to plate tectonics, We don't have much direct information on the early stages of the the Earth's history. But I've never understood why it was assumed that (much of) the Earth's water hasn't been there since our planet coalesced. Of course, I've also never understood the necessity to invoke an improbable planetary collision to explain the moon. It's not like binary pairs of large objects are rare in the universe.

    And even if the water did come entirely from cometary impacts after formation, why would that preclude lots of other watery planets? Are comets assumed to be rare in other planetary systems? Why?

    --
    You can't see ANYTHING from a car, You've got to get out of the goddamned contraption and walk...Edward Abbey
    1. Re:why not? by ljw1004 · · Score: 1

      I've also never understood the necessity to invoke an improbable planetary collision to explain the moon. It's not like binary pairs of large objects are rare in the universe.

      Earth and the Moon have different compositions. So they can't both have been formed in the same way.

    2. Re:why not? by vtcodger · · Score: 2

      "Earth and the Moon have different compositions"

      As I understand it, the composition of the two bodies is quite similar. In fact that's the primary reason that the collision theory was formulated. In the collision theory, they moon is composed primarily of material blasted from the Earth by the collision. see https://en.wikipedia.org/wiki/...

      --
      You can't see ANYTHING from a car, You've got to get out of the goddamned contraption and walk...Edward Abbey
    3. Re: why not? by Anonymous Coward · · Score: 0

      If you don't understand why theories say something and want to know, maybe you should read more about them, and not from a popsci source. There is a lot written already on why the composition of the moon makes it not look like it formed on its own and issues with it forming next to Earth or being captured. There is also a lot written on trying to figure out what happened to volatile elements on the early Earth.

    4. Re:why not? by Hognoxious · · Score: 1

      Different in the sense that the Earth consists of corey stuff and crusty stuff and the moon only has crusty stuff?

      I mean it's not possible that the impact only whacked the outside off, or that whichever fragment got biggest fastest snagged all the heavy shit, is it?

      --
      Confucius say, "Find worm in apple - bad. Find half a worm - worse."
    5. Re: why not? by vtcodger · · Score: 0

      Well yes. There's a lot written. But there are a horrendous number of loose ends in ALL of them. If I understand correctly, they can't even get a computer model to actually assemble a moon of the correct size in the right place after a modelled collision. Given the ... ahem ... flexibility ... computer modelling, that in itself is a pretty huge difficulty.

      Which volatile elements are you thinking of? The two very light gases -- Hydrogen and Helium -- are gone as significant atmospheric components. Is that a surprise? Why? The next most massive volatiles -- ammonia, methane, water are still around? Or were you thinking about the moon? I vaguely recall that there is an issue with the volatile gases there not matching expectations, but I don't recall (if I ever knew) the details..

      --
      You can't see ANYTHING from a car, You've got to get out of the goddamned contraption and walk...Edward Abbey
    6. Re: why not? by Anonymous Coward · · Score: 0

      Which volatile elements are you thinking of?

      Volatiles in that context doesn't have to do as much with their atomic mass, but with the chemistry and propensity to bond with different things at different temperatures. People often assume that what sinks to the core of a planet, what is found on the surface, and what floats away into space is just separation by the atomic mass, but instead has a lot to do with what bonds or dissolves in what, and the relative proportions. This has been pretty heavily studied in the context of radioisotope dating as there are plenty of isotopes that decay from one category to another (e.g. from siderophilic to lithophilic). So in that sense, volatiles can include things like selenium and tellurium.

    7. Re:why not? by Anonymous Coward · · Score: 0

      Earth and the Moon have different compositions. So they can't both have been formed in the same way.

      The only real difference is that the Moon cooled faster (at all) thereby ensuring many of the heavy elements didn't sink into the core.

  9. Re: God's truth wins again by Anonymous Coward · · Score: 0

    Depends on the size of the snowball, and if they included a rocky center. You would need a rocky center for there to be left a trace. After all, if you didn't see it, did it exist? The extrapolation is make believe, just as fiction or sci-fi. But now they are rehashing the rehashed leftovers trying to split the chefs hairs?

  10. Why either - or? by Viol8 · · Score: 2

    Why couldn't it have been a combination of water from the proto earth and asteroids and comets later on? There's little doubt the earth was bombarded for millions of years after it formed so it seems silly to pretend that didn't deliver any water to the planet.

    1. Re:Why either - or? by vtcodger · · Score: 1

      "Why couldn't it have been a combination of water from the proto earth and asteroids and comets later on?"

      Seems like substantial water contributions from comets would almost certainly have to be the case unless we somehow totally misunderstand the nature and composition of comets or assume that they somehow avoid ever impacting the Earth.

      --
      You can't see ANYTHING from a car, You've got to get out of the goddamned contraption and walk...Edward Abbey
  11. Water(water ice) is plentiful ... by evanh · · Score: 1

    ... throughout the solar system, and, by extension, abundant everywhere. Earth formed containing plenty, as every celestial body will. It would have all been fine crystals initially. Now I'll just whip back in my TARDIS and grab some early samples to prove my hypothesis.

  12. Re:mere speculation like this science? by Anonymous Coward · · Score: 0

    How else you gonna keep the universities full?

  13. Why is this an issue? by Anonymous Coward · · Score: 0

    Surely we know all about Earth's hydrological history and the science is settled, right? We had a scientific theory, so that's it - it's settled.

    OR

    Perhaps the "science" conducted by sitting in a room with a computer and day-dreaming about what "would-a/could-a/should-a happened" long ago with lots of conjecture about the possibilities we can imagine but not proof of what ACTUALLY happened might not be so certain and final. It's not easy to prove any of it or even to exclude the numerous possibilities the current generation of day-dreamers have not even considered.

    Wake me up when somebody invents an actual H.G. Wells-style time machine that lets us go back and see what really happened; until then, this is all academic, but with all the credibility, authority and scientific legitimacy of a "reality TV" show.

    1. Re:Why is this an issue? by Immerman · · Score: 1

      Studying the distant past is difficult, and the science is anything but settled. So we speculate and come up with various hypotheses that we share around. Then we collectively try to punch holes in them and consider their implications - what we'd expect to see today if it were true. We then go looking to see what's actually there. Maybe it supports the hypothesis, maybe it supports the older, more widely accepted story, or maybe it's something completely unexpected that makes you question things you thought you knew.

      That's science in action - retelling and refineing an endless, ever-changing story about the way the universe works. Everyone knows it's at least partially fiction around the edges - there's just too many holes in it for it to be absolute Truth, but the story keeps stretching and changing as we try to patch up the holes - and every new patch promises the possibility of revealing new things about the universe - maybe new details of physics or material science that we can exploit in useful ways. Maybe hints as to other places we can look for even more clues.

      --
      --- Most topics have many sides worth arguing, allow me to take one opposite you.
  14. Life = Improved Water Acquisition/Retention by Anonymous Coward · · Score: 0

    Not so different from trace water on the Moon but on grander scale.

    Enough mass for captive atmosphere
    + Great Oxygenation Event cyanobacterial critters emitting O2
    + UV light splitting the O2
    + free H from solar wind
    = H2O forming in the upper atmosphere, no comets required

  15. Well.. by minkowski76 · · Score: 1

    Earth clearly has water, and we think Mars was much, much wetter billions of years ago, and many scientists theorize Venus once had an abundant liquid water supply, so if so, that's three planets within a band of the Solar System, and thus is stands to reason that liquid water exists at least in similarly configured extra solar systems, right? Of course that doesn't answer the question of whether water is either endogenous or exogenous, or a little of both, but if asteroids and comets can carry water, enough to populate perhaps three planets, why can't the planets themselves carry a proportional abundance of water? Then again, I'm no planetologist, so I'm probably barking out my asshole.

  16. Water planets may abound by tompaulco · · Score: 3, Interesting

    " If true, the results suggest that water-rich planets may abound in the universe."
    Or if the other theory about asteroids is true, then water-rich planets may abound in the universe. So this changes nothing. Also, both theories explain why all the planets in our solar system are so rich and abundant in water. Except that they are not.
    Hydrogen is the most common element in the universe, making up about 3/4 of the mass of the universe. Oxygen is the third most common, but the 2nd most common, Helium, takes up almost 1/4 of the mass of the universe. Oxygen makes up about 1/70th as much mass in the universe as hydrogen. However, somewhat unique on Earth, Oxygen makes up about 64% of the mass of Earth. Atmospheric Oxygen in the other planets is negligible, and even Oxygen combined in other compounds on other planets is a much smaller percentage than on Earth. Oddly, Hydrogen is relatively uncommon on Earth when compared to its abundance in the rest of the universe.

    --
    If you are not allowed to question your government then the government has answered your question.
    1. Re:Water planets may abound by Anonymous Coward · · Score: 0

      If there are stars in the universe, then there is hydrogen. If there is fusion, then there must also be Helium, Beryllium, Carbon-12, Oxygen. Once you have Oxygen and Hydrogen, you get Water (H2O). All elements created through fusion.

      http://cronodon.com/SpaceTech/Nuclear.html

      Those ratios seem to indicate how so little of the universe has been converted by stellar fusion.

    2. Re:Water planets may abound by dryeo · · Score: 1

      I doubt very much that oxygen makes up 64% of the mass of the Earth. Do you have a citation?
      According to https://en.wikipedia.org/wiki/..., the main composition of the Earth by mass is iron at 32.1% though I am somewhat surprised that oxygen is number 2 at 30.1%, which is a lot of oxygen. There are estimates that put the percent of oxygen in the crust at 47% which is close enough to half but still not 64%. And of course the atmosphere is mostly nitrogen at aprox 78% and almost 21% oxygen, thanks to the hard work of plants.

      --
      https://en.wikipedia.org/wiki/Inverted_totalitarianism
    3. Re:Water planets may abound by tompaulco · · Score: 1

      I tried to go back through my history and see what sites I visited and where I might have gotten the 64% number. However, I wasn't able to find the site where that number came from. I would have to guess that I was cruising wikipedia, based on the history. Perhaps somebody updated the article. It does show 47% or 49% (depending on which article you read) in the crust as you mention, and also 88% in the ocean and 23% (by mass, 21% by volume) in the atmosphere. The mantle also contains about 41% by mass of Oxygen and is much bigger than the crust. The core does not contain oxygen in any large amount.

      --
      If you are not allowed to question your government then the government has answered your question.
    4. Re:Water planets may abound by dryeo · · Score: 1

      Probably just a typo somewhere or if you're like me, a mental hiccup. Shit, I thought that I said by mass for the total and yet I obviously didn't and of course the atmosphere numbers I quoted were by volume which I missed, having found the numbers I remembered.

      --
      https://en.wikipedia.org/wiki/Inverted_totalitarianism
    5. Re:Water planets may abound by Anonymous Coward · · Score: 0

      You actually have a grasp of the basics. How refreshing in this discussion. If an AC can upvote another AC, you would have my vote. However...
      18Oxygen has always been a problem in the Models of Primordial Nucleosynthesis.
      Its production Cross Section is so vanishingly low, that we should barely even be able to measure its presence.
      Yet, in contrast, we have shitloads of 18O.
      The most plausible explanation for this is Neutron Capture during the Death Throes of previous generations of Stars. Thus 16O to 18O ratios give us a rough idea of how many stellar Generations have occurred.
      The 18O to 16O ratios in Cometary Water are roughly the same as that found down here, everywhere. The Water may not have come from the same sources, but it is all equally old. A puzzle.
      The 18O to 17O ratios are also interesting, since 17O _can_ be explained by the processes of Primordial Nucleosynthesis, as well as by Neutron Capture... Which means that by any plausible Model, there should be much more 17O than 18O. But there isn't. (See Urey.)
      Another puzzle.
      So our Models aren't wrong, they are just incomplete; we need to throw more money at them for more completeness.
      This isn't a joke. Yes, throw more money.
      It's better than the usual flinging of handfuls of crap, all too commonly flung by the Slashdot Monkeys.

  17. Re:God's truth wins again by Anonymous Coward · · Score: 0

    Traditionally genesis is not interpreted literally. Its been mainly a nut case interpretation all along that it was meant literally.

    http://www.myjewishlearning.com/article/genesis-as-allegory/

  18. Don't forget the moon! by anwyn · · Score: 3, Interesting

    Remember the current theory of the formation of the moon! The collision could eject a huge amount of H (in various forms), into space. This gives an opportunity for isotopic sorting, the lighter H having a greater chance of being blown away by the solar wind, the heavier having a greater chance of coming back.

  19. Maybe it is both by Anonymous Coward · · Score: 0

    The article implies an either/or scenario instead of the idea that both hypotheses could be valid: water was present during the forming of the earth and water was also supplied by asteroids and comets.

  20. Re:God's truth wins again by FatdogHaiku · · Score: 1

    The important question isn't how, but why.

    The flying spaghetti monster gave us water so that we could boil pasta.

    So what your hinting at is that the flying spaghetti monster likes to get eaten?
    I guess I can understand that...

    --
    You have the right to remain sentient. If you give up the right to remain sentient, you will be elected to public office
  21. Isotopic composition by Cacadril · · Score: 2

    The article says that the comets are much richer in deuterium than Earth's water. The small inclusions of water in primordial rocks match the isotopic balance of sea water. That is why the comet theory is now relatively disfavored.

    But how did the isotopes get differentially distributed in the primordial cloud, so that the deuterium collected in the outer regions where the comets formed, rather than in the region between Jupiter's orbit and the Sun itself?

    --
    There is no substitute for common sense. Especially, no body of rules will do.
    1. Re:Isotopic composition by Anonymous Coward · · Score: 1

      Deuterium has enough of a mass difference with hydrogen that the chemical and physical properties differ a little. Processes that involve adsorption, freezing, and sublimation, like on a comet, can cause small changes in the isotropic ratio. The effect is quite small, but measurable. Even processes like the fixation of carbon by plants can cause measurable changes in isotropic ratio from subtle chemistry differences.

    2. Re:Isotopic composition by Cacadril · · Score: 1

      But then the isotopic composition of the water carried by the comets may have changed since the time when they supposedly brought water to the Earth? It's a long time since, and I would think that hydrogen diffuses more readily than the heavier deuterium.

      --
      There is no substitute for common sense. Especially, no body of rules will do.
    3. Re:Isotopic composition by Anonymous Coward · · Score: 0

      I think that you meant to say "Isotopic Ratio". That's OK, it happens to all of us.

      This is why one shouldn't put too much value in the H-D ratios. There are too many variables.
      16O-17O-18O ratios are much more stable around our neck of the Universe.
      Even better are the 20Ne-21Ne-22Ne and 28Si-29Si-30Si ratios.
      Wherever our Comets formed, in terms of the Age of the Universe, they are quite young, as are we.

      (The Power is now out; probably some drunk has taken out the same utility pole up the street that they all seem to favor. So who knows when I shall actually post this. Here I am, typing away in the Dark at 3:35 AM, on an old Apple Macbook Air, with 10:45 hours remaining on the Battery. The Furnace is now out as well, so it's going to get cold.)
      (3:41. Hmmm... I just checked outside. The houses on the Hill are also dark; they are on an entirely different PG&E Branch line...)
      (3:53. It's so _quiet_. The loudest sound in my house is the cluck-cluck-cluck of my Living Room Clock, which has its own Battery. I can't even hear the traffic sounds on the Expressway a quarter mile away. Even at this late hour, there is usually _some_ traffic noise...)
      (4:09. Now it's raining. Just a few drops. That explains the quiet. Did you know that Rain carries the metallic seeds of Meteorites? It's true, and it's an excellent 8th Grade Science Project.
      For this, you will need an old Aluminum Cookie Sheet, and an old Loudspeaker Magnet. Place the Cookie sheet with the Magnet taped securely underneath at a slight angle outside so that some rain can accumulate. Leave it out for a few days. Then let it dry, remove the magnet, swipe just over where the magnet was, and examine under a Microscope. Microscopic Meteorites. This doesn't work for the Stony variety. 10:06 hours left on the Battery.)
      (4:14. I just heard a long low beep. From where, I don't know. So many things can beep in the Dark. There it is again! It's coming from the bedroom.)
      (4:21. It's the Atomic Clock by the bed. Damn it, I _know_ that the Power is out. Time to grab the Car Keys, and check the radio.)
      (4:32. A couple of houses up the hill now have ghostly lighting, the tell-tale trails of LED fed Phosphors. Nothing on the radio so far. The Macbook says that I now have 14:27 hours remaining. It is lying. I hate it when it does that. KCBS is doing a story about the LHC.)
      (4:38. It's a 60 Minutes piece about the LHC on KCBS. It isn't as awful as it could have been. The NYT completely botched my interview about Element 118.)
      (4:43. KCBS is now doing a bit about Rap Music and Alexander Hamilton. Switch to KGO. Very confused; it sounds like they are doing Negativland from three decades back, but with commercials.)
      (4:48. Five minutes straight of commercials now. Back to the Program. Something about Battles in the Pacific, but with Background Music and sound effects. Just waiting for a mention of Howland Island. Now raining heavily, but it smells great. Macbook says that I have 14:39 hours remaining. It has turned back time. Check Wifi- a whole bunch of addresses that I've never seen before pop up, mostly DSL. Sadly, all locked down. I've never checked from the driver's seat of my old Mercedes wagon before. Nutjob on KGO is still fighting WWII, and defending MacArthur. Where do they find these loons?)
      (4:59. Back to KCBS. Talking about Paris... but that after this...)
      (5:10. 50% Paris, 50% Commercials. What about the Comet that wiped out my neighborhood, leaving only me?)
      (5:18. Review of Republican Presidential Aspirant's opinions on Paris, among other things. They all really loathe each other. Why should any of us like even one of them? 12:48 remaining on the Battery. It's stopped raining.)
      (5:27. No local news yet. I once actually spent some time and effort documenting the power usage of this Macbook Air. With Wifi and Bluetooth off, Backlight up two ticks, and keyboard lighting at minimum, it consumes ~3.8 Watts, as System Profiler reports. That can't be trusted of course, so I broke o

  22. Re:God's truth wins again by Anonymous Coward · · Score: 0

    The flying spaghetti monster giveth its body to true believers, so they acquire Its divine wisdom.

  23. Re:God's truth wins again by Anonymous Coward · · Score: 0

    Ah. Like zombie Jesus! lol.