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Space Science

Was Earth a Migratory Planet? 257

astroengine writes "Why our planet isn't a "snowball Earth" — a dilemma called the 'faint young sun paradox' — has foxed solar and planetary scientists for decades. Since the Earth's formation, a planet covered in ice should have stifled any kind of greenhouse effect, preventing our atmosphere from warming up and maintaining water in a liquid state. Now, David Minton of Purdue University has come up with a novel solution that, by his own admission, straddles science fact and fiction. Perhaps Earth evolved closer to the Sun and through some gravitational effect, it was pushed to a higher orbit as the Sun grew hotter. But watch out, if this is true, planetary chaos awaits."
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Was Earth a Migratory Planet?

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  • On the upside though (Score:4, Interesting)

    by Fluffeh ( 1273756 ) on Wednesday April 18, 2012 @07:21PM (#39729469)

    If this is the case, and the "chaos" that awaits is us migrating into a higher orbit, then whoopee, there goes us having to worry about the greenhouse effect... Oh wait... this isn't just another excuse not to curb our burning of fossil fuels is it?

    • If this is the case, and the "chaos" that awaits is us migrating into a higher orbit, then whoopee, there goes us having to worry about the greenhouse effect... Oh wait... this isn't just another excuse not to curb our burning of fossil fuels is it?

      How many billions of years are you planning to live?

      • by Fluffeh ( 1273756 ) on Wednesday April 18, 2012 @11:53PM (#39731105)

        How many billions of years are you planning to live?

        Ideally as many as I can.

        I of course plan to get fashionably mad into my second billion, but the recover after a bit of time in some choice facility. By that time though, I should have enough money to pay for absolutely anything, I deposited six dollars into a compound interest savings plan a week ago Tuesday.

      • Hey, I want to see that planet go pop, so keep moisturizing me!

    • by Bruha ( 412869 )

      Not true, the sun gets about 1% brighter every million years so if we move away slowly then maybe that counteracts the increase in light output.

      There's a theory out there that believes as the sun loses mass the planets move away slowly, so perhaps by the time the sun is a red giant, we would be far enough away to not get toasted.

      • by Fluffeh ( 1273756 ) on Thursday April 19, 2012 @02:21AM (#39731517)

        That would make perfect sense that as the sun loses mass the planets drift further away, but the problem is that the size of the sun is driven not only by the mass, but the available fuel driving the fusion reaction inside it. The radius of the sun is maintained by the amount of energy being released in its core through fusion which pushes against the force of gravity pulling the sun together. Certain elements fuse releasing a lot of energy, others fuse releasing only a little energy - yet others fuse and take in energy from their surroundings. The tipping point is Fe (Iron), anything lighter releases energy when it is fused, anything heavier absorbs energy. While sun has converted about 100 earth masses into energy over the 4.5 billion years it has been here, it is still fusing mainly Hydrogen (lots of energy output), meaning that by the time it reaches red giant phase in about another 5.5 billion years, it will have used up a bit over another 100. The problem is that it has around 330,000 times as much as the Earth. It is losing mass through fusion, but not nearly enough to increase the orbital radius of the planets by the time it reaches the red giant phase.

      • by Fluffeh ( 1273756 ) on Thursday April 19, 2012 @02:26AM (#39731537)


        the sun gets about 1% brighter every million

        is wrong. The sun is getting brighter at the rate of 10% every billion [wikipedia.org] years.

        Short and Long [wikipedia.org] scales aside, a billion years is at minimum 1,000 million (or a million million if you use the long scale) - both of which are orders of magnitue different to what you claim.

  • by Anonymous Coward on Wednesday April 18, 2012 @07:24PM (#39729505)

    Earth is migratory

    In fact, Earth received a Blue-green card as early as 3.5 billion years ago after passing a solar naturalization test.

  • Funny pages (Score:4, Funny)

    by paiute ( 550198 ) on Wednesday April 18, 2012 @07:26PM (#39729519)
    "And then a miracle occurs" makes a good punchline but lousy science.
    • Re:Funny pages (Score:4, Insightful)

      by Guppy06 ( 410832 ) on Wednesday April 18, 2012 @08:00PM (#39729827)

      It makes for fantastic science if you then go on to investigate and describe the miracle. "Oh, wow! How did that happen?"

    • Hey, "a wizard did it" is basically the foundation of intelligent de... ok, you're right, good punchline but lousy science.

      • Hey, "a wizard did it" is basically the foundation of intelligent de... ok, you're right, good punchline but lousy science.

        The Greeks were cynical about the Deus ex Machina even in entertainment. It's a total wash for science.

  • by busyqth ( 2566075 ) on Wednesday April 18, 2012 @07:26PM (#39729533)
    It is the consensus of 99% of climatologists that the earth isn't a snowball and therefore it is a fact that the earth has slowly moved into a higher orbit at exactly the same rate that the sun has warmed so as to maintain a climate on earth appropriate for life. The more we fill the atmosphere with greenhouse gases and thus heat the earth, the further the earth will move away from the sun so as to maintain an optimum climate. These "inconvenient truths" prove that there is an intelligent designer of the universe.

    • Re: (Score:3, Funny)

      by Anonymous Coward

      It is the consensus of 99% of climatologists that the earth isn't a snowball and therefore it is a fact that the earth has slowly moved into a higher orbit at exactly the same rate that the sun has warmed so as to maintain a climate on earth appropriate for life. The more we fill the atmosphere with greenhouse gases and thus heat the earth, the further the earth will move away from the sun so as to maintain an optimum climate. These "inconvenient truths" prove that there is an intelligent designer of the universe.


      Dude, if you can get a creationist to accept enough science to admit that anthropogenic global warming is real, that miracle itself is enough to prove the existence of God.

    • Re:Conclusions... (Score:4, Insightful)

      by rtb61 ( 674572 ) on Wednesday April 18, 2012 @09:17PM (#39730371) Homepage

      In the game of interstellar billiards quite unusual things can happens to planets over time. Slowly moving to higher orbits is not one of them. Interacting with other high gravity masses is, whether it's a object passing through the solar system upon it's own intergalactic trajectory causing a direct change or that object impacting other high gravity masses and causing an indirect change or usual orbits of high gravity masses within a system.

      For decades science has avoided catastrophic based planetary orbits, it makes for messy science but over millions of years in a much more interactive galaxy and universe than originally thought, much to the fear of us tiny rock in space dwellers, catastrophic orbital patterns are all too common.

      Catastrophic orbits of course imply major life extinguishing impacts, that's were the catastrophe part comes in and of course that's why science doesn't like to think about them too much.

      Although it allows the hypothesis of much simpler and more logically planetary development models and those planets out of sequence being treated as just the result of catastrophic interactions, it leaves those scientist with such a gut wrenching sense of impermanence that emotion over rules logic and far more stable convoluted models are preferred.

    • by Red Flayer ( 890720 ) on Wednesday April 18, 2012 @10:00PM (#39730605) Journal
      Perhaps you should re-read the canon.

      Book Secondi 3:12

      Lo, for the baking of the divine meal
      Let it be done that the goliath meatball[1]
      Be moved upon the table[2]
      At such distance that the woodfire oven[3]
      Provides a strong heat source to allow for the Maillard reaction
      To properly crustify the goliath meatball
      And then let it be moved
      To a sufficient distance, where it may
      Yet leave the inside full of tenderness
      Like the twin meatballs upon the bosom of a mother
      His Noodly Appendage shall make such adjustments
      Necessary to make it so.


      [1] the goliath meatball being our planet.
      [2] the table, sometimes mistranslated as "the firmament", is of course, the fabric of spacetime
      [3] there is some disagreement among scholars about this translation, but we know from context that this is the sun

      Clearly, from analysis of scripture, we can determine that the Master of the Heavenly Forkful moves or planet into a lower or higher orbit to ensure that it cooks properly.
  • Planet migration theories have been floating around since the 1970s. Nothing new, but I guess Discovery's standards are continuing to fall.
    • by Artifex ( 18308 )

      I guess Discovery's standards are continuing to fall.

      Last time I went to the site I saw articles on things like alien abduction.

  • Doesn't it suggest that the Earth was heated up a lot at the time? That could have jumpstarted the greenhouse engine.
    Could have altered its orbit, too, probably.

  • by Brad1138 ( 590148 ) <brad1138@yahoo.com> on Wednesday April 18, 2012 @07:36PM (#39729605)
    Kind of like this [wikipedia.org]...
    • Wouldn't a giant impact change its orbit? Kind of like this [wikipedia.org]...

      The moon-creating impact was my first thought also. But I can imagine that it may also have heated things up a bit on its own, all without significant chaneg of orbit.

    • The giant impact lunar origin theory got a little less likely just recently. The original article in Nature Geoscience is behind a paywall, but you can read a summary at http://www.space.com/15035-moon-formation-theory-challenged.html [space.com].

      Basically, titanium isotope signatures from Earth and lunar samples are identical. For the giant impact theory to be correct, the impactor would have had to have the same titanium isotope mix as Earth, which seems unlikely if it originated elsewhere/when in the solar system's

      • Why the Giant Impactor Theory assumes a different isotope mix for the impactor?

        From what I understand, they had to have rocks brought back from the Moon to actually measure their isotope mix, so my guess is that we don't accurately know the isotope mix of anything besides the Earth and the Moon. How do we know it isn't the same mix everywhere in the solar system?

        Disclaimer: I'm clueless about all this, I'm only asking questions.

        • by dave420 ( 699308 )
          Because things made in different places at different times will have different isotope mixes. It would be a fantastic coincidence if the mixes of the impactor and proto-Earth were identical.
  • by Lord_of_the_nerf ( 895604 ) on Wednesday April 18, 2012 @07:46PM (#39729691)
    Up until it found it was having humans. Then it had to settle down.
  • There are a lot of "maybe"s out there when it comes to these science theories and discoveries, but adding a "watch out" for planetary chaos at the end is so drama-llamas. I'm not going to worry, because even if it came about, wtf can I (or anyone) do about it? Gotta live out what we got in the here and now while doing our best to observe the future--rationally, not Mayan-Calendarly.

  • It's not that novel (Score:5, Informative)

    by Daetrin ( 576516 ) on Wednesday April 18, 2012 @08:06PM (#39729911)
    Well, unless he's trying to be punny. Migratory planets were proposed by Immanuel Velikovsky [wikipedia.org] in, among other things, his 1950 book "Worlds in Collision" [wikipedia.org]. His ideas were picked up by James P Hogan [wikipedia.org] for his "Giants" series [wikipedia.org] and other books. (James P Hogan was notable for adapting crazy theories into interesting books in his early years, but then digressing later in life to the point where he never met a conspiracy theory he didn't like.)
  • by gstrickler ( 920733 ) on Wednesday April 18, 2012 @08:42PM (#39730181)

    it was brought here by a European Swallow?

  • The Inside Scoop (Score:5, Informative)

    by spacemandave ( 1231398 ) on Wednesday April 18, 2012 @09:30PM (#39730455)
    Ah, so here's the deal. I'm the person that this article is talking about (David Minton, professor at Purdue University). I've been reading Slashdot for a fair number of years now, though it took me a long time to sign up and comment for the first time (I've always been a lurker at heart). Because I have a soft spot for all you basement dwellers (I kid!), I'm going to give you a bit of behind the scenes regarding this article, which kind of took me by surprise, actually. This is a bit long, so TL;DR: Science sometimes happens during panicked last minute coding sessions in hotel rooms prior to delivering invited talks that were procrastinated about.

    So about five years ago my graduate school advisor and I wrote what was my very first peer-reviewed paper, which was on the subject of the Faint Young Sun Paradox. The paradox goes something like this: The early Sun was fainter than it is today, so all things being equal the Earth should have spend the first half of its life frozen over. Geologists tell us it wasn't, so something wasn't equal. What was it? We investigated the idea that the Sun may have been slightly more massive (something like 2-7% more massive), and that it had to lose most of that excess mass over a few billion years, which is at odds with measurements of mass loss of Sun-like stars. So we published it, and I went on to do other things in grad school, mostly involving trying to figure out the early impact bombardment history of the solar system, which we think may have been influenced by an early period of migration of the gas giant planets.

    Fast forward to a few months ago, and a fellow at the Space Telescope Science Institute (the place they run the Hubble from) contacted me to ask if I'd like to give a talk about my old mass-losing Sun paper at a workshop that was planned to bring together astrophysicists, geologists, climate scientists, and planetary dynamicists to talk about the Faint Young Sun problem. They wanted me to also talk about planet migration and how that might fit in to the problem. Sure, why not? Revisiting the problem would be fun! The thing is, I've just started a new faculty job, and part of my job is helping get a new planetary science group built up at Purdue, so I've been extremely busy. And, well, I procrastinated. Big time. There was always some pressing thing to do that took time away from getting ready for the workshop. So the next thing I know, it's a few days before the meeting and I still haven't really thought about the faint Sun in about five years. So I dust off my old files, start futzing around with a talk, and the next thing I know I'm on a plane to Baltimore.

    Late the night before the workshop is about to start, I'm racking my brain trying to come up with something new to say. You see, I've been thinking about early solar system history, and planet formation. Migration is a big deal in those early days. It's easy to get planets to move around in young solar systems. But the Faint Young Sun problem is a problem for the Earth's mid-life, not it's adolescence. Then I remembered a paper I really liked that came out a couple of years ago by Jaques Laskar and Mickaël Gastineau. They showed that our own solar system could potentially destabilize after a few billion years of seeming-stability due to Mercury's proximity to a chaotic region. It's described briefly here: http://en.wikipedia.org/wiki/Stability_of_the_Solar_System#Laskar_.26_Gastineau [wikipedia.org]

    What if something like that had happened *already?* So I futzed around with an N-body gravitational dynamics code remotely from my hotel room, in my pajamas, playing around with plausible initial solar systems where Earth stared just a tad closer to the Sun, but close enough to solve the problem of being frozen over, and Venus started out as two separate planets and then went unstable after many billions of years, scattering Earth to its present location in the process. And, when I checke
    • Re:The Inside Scoop (Score:5, Informative)

      by IonOtter ( 629215 ) on Wednesday April 18, 2012 @10:53PM (#39730873) Homepage

      Slashdot needs a moderation code for Awesome.

      Thank you, sir!

    • Does your theory take into account the additional heat generated by tidal forces when the moon's orbital radius was smaller?
      • Re:The Inside Scoop (Score:5, Interesting)

        by spacemandave ( 1231398 ) on Wednesday April 18, 2012 @11:19PM (#39730957)
        During the Archean, the time period relavant to this study, tidal heating was not terribly important. The larger internal heat from radioactive decay was higher, yet still dwarfed by the energy input from the Sun in setting the surface temperature of the Earth.
    • by bindo ( 82607 )

      With all the "bad", this post is one of those things that remind me why I've been lurking around here for so many years.


    • I always thought it was the solar wind. Sun gets hotter, wind blows stronger. Slowly, over perhaps a billion years, it will alter Earth's orbit.

      It should buy me a little time when the Sun starts dying, as the wind slacks off. Earth should then start falling closer.

      • That was the subject of my 2007 paper. The problem is that the present-day mass loss rate of e Sun due to solar wind and coronal mass ejections is tiny. The Sun loses more mass do to the conversion of mass to energy in the core, and it's not enough to appreciably change the mass of the Sun over the age of the solar system. Young Sun-like stars appear to have stronger stellar winds, correlated with their higher rotation rate. But the Sun would have had to sustain orders of magnitude higher mass loss than pre
    • I'm terribly sorry, Professor Minton, but didn't the early Earth had far greater volcanic activity, a thinner crust, a hotter mantle, faster plate tectonics, and meteors constantly hitting it?

      • Re:The Inside Scoop (Score:5, Informative)

        by spacemandave ( 1231398 ) on Thursday April 19, 2012 @11:46AM (#39734585)
        Hi, good questions. The time period relevant to this is the Archean [wikipedia.org]. The interior of the Earth was warmer back in the Archean than it is now, and there may have been more volcanic activity, but it's difficult to know what style of tectonics was operating at the surface. Very few rocks survive from that time period. Now one proposed solution to the Faint Young Sun problem was just that there was a lot more CO2 in the atmosphere. The subject of a few talks at this workshop a couple weeks ago was constraining the abundance of atmospheric CO2 from looking at the chemistry of the few rocks we have from that epoch. There were some presentation suggesting that the atmosphere contained no more than about 20x the present abundance of CO2, but you may need more like 100-1000x in order to completely solve the problem. So people have suggested things like more CH4, NH3, and also that perhaps the Earth was somewhat darker due to different styles of cloud-making and fewer continental land masses (oceans are quite dark), meaning that the surface did not reflect back as much radiation as it does now. All of these ideas are being actively debated.

        Now as to the question of meteor bombardment: that was the topic of the last 1/3 of my talk at the workshop, but was not mentioned in TFA. I am on a paper coming out in a couple of weeks that is showing that the so-called Late Heavy Bombardment persisted on the Earth all throughout the Archean, rather than ending abruptly at the end of the Hadean, as was thought from looking at lunar samples. The bombardment rate, while much higher than present-day, was not so high as to likely have had any major direct effect on the climate over geologically interesting timescales (say an impact creating a 1000 km wide basin occurring every 200-500 million year during the Archean). However, there may have been indirect effects of impact bombardment that have yet to be explored, and we find that it is an interesting coincidence that bombardment rate pretty much drops off completely by the early Proterozoic, just as Earth began to show signs of having some oxygen in the atmosphere, and the first real evidence for any kind of major glaciation events (the Huronian snowball). Could somewhat elevated impact bombardment rate be a controlling factor in the warm and anoxic Archean? I don't know the answer to that, but were studying it.
  • That makes no sense. Early in Earth's life it was a molten ball of lava because it was just forming and it had a heavy atmosphere since volcanoes spit out green house gasses like crazy.
    As far as I knew early in Earth's life it was extremely hot, as even after life starting it was far far hotter then now and far too hot to have snow/ice.

    • Yes, that's the paradox: the early Earth was warmer than it "should" have been, given what we (think we) know about solar output, greenhouse gases, etc. at the time.

  • We have been a "snowball Earth", but life changed that some 2-3 billion years ago. http://en.wikipedia.org/wiki/Cryogenian [wikipedia.org]

    Without life, Earth would probably have remained a snowball Earth.

    What is the problem?

  • by ctrl-alt-canc ( 977108 ) on Thursday April 19, 2012 @03:37AM (#39731729)
    One of the amazing consequences of the Kolmogorov-Arnold-Moser theorem [math.ethz.ch] (KAM) is that the Earth orbit is stable, despite the influence of Jupiter. Stable in this context means that the orbit perturbations caused by Jupiter and the other planets don't cause the Earth orbit to move too close or too far from the Sun, causing dramatic changes of temperature.
    Chaos theory when gravitation is involved is not so chaotic as one could expect: the KAM theorem tells us that multi-body systems governed by gravitation law have intrinsic stability regions.
    • by spacemandave ( 1231398 ) on Thursday April 19, 2012 @11:25AM (#39734309)
      The problem is not Earth's stability, it's Mercury's. Mercury is close to a so-called secular resonance, and it's eccentricity varies more chaotically than Earth or Venus. So yes, Earth would remain bounded indefinitely as long as Mercury never attains a high enough eccentricity that it begins crossing into Venus's orbit. Once close encounters take place with Mercury, the whole inner solar system can rapidly destabilize.

(null cookie; hope that's ok)