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Moon Space Science

No Moon Needed For Extraterrestrial Life 246

Posted by Soulskill
from the sheer-luna-cy dept.
sciencehabit writes "Given the generally accepted idea of how Earth got its big moon — through a dramatic collision with a Mars-sized body that knocked a huge chunk of Earth loose — astronomers estimate that only 1% of all Earth-like planets in the universe might actually have such a hefty companion. That would mean planets harboring complex life might be relatively rare. But researchers have now carried out large numbers of detailed numerical simulations of 'moon-less Earths,' which show that the consequences are less dire than is generally assumed. According to the simulations, these planets would have ample time for advanced land life to evolve. As a result, the number of Earth-like extrasolar planets suitable for harboring advanced life could be 10 times higher than has been assumed until now."
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No Moon Needed For Extraterrestrial Life

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  • YAY! We can be safe from Werewolves on these 'that's no moon' planets.

    Also, "10 times higher" did they just pluck that number out of thin air?

    • Re: (Score:3, Insightful)

      by sharkey (16670)
      Possibly someplace darker and smellier.
    • by arisvega (1414195)

      did they just pluck that number out of thin air?

      No, what they pluck out of thin air is what "advanced life" is. Unless they mean "life as we know it".

  • I've seen several articles now about how much water is in the center of the moon, calling in to question this theory about the origin of the moon. I've never liked this origin theory, anyway. The large gravity well of a bigger object pulled in a smaller object. Boom, easy stuff. And how in the universe can someone talk about how unlikely it is that other planets would have moons, when our own solar system has several planets with moons? A quick google search reveals this image: http://upload.wikimedia [wikimedia.org]
    • Re: (Score:3, Insightful)

      by zav42 (584609)
      I think you misunderstood. The uniqueness is not in the fact that it has a moon but in its extraordinary size (in relation to the planet size). That IS quite unique and it may be essential to life development. Or it may not... IMO its a strange approach to try to solve this question with a simulation. The outcome seems to depend on lots of factors whose influence on the development of intelligent life are just not known yet. Without knowing how intelligent life develops a simulation seems like just guesswor
    • by gstoddart (321705)

      And how in the universe can someone talk about how unlikely it is that other planets would have moons, when our own solar system has several planets with moons?

      Because, the default position has been that life is exceedingly difficult to make happen, and that you needed a truck-load of favorable conditions to even hope it could happen. I think the notion was that we were a rare and unique solar system.

      I seem to recall in the late 80s/early 90s when the notion of finding an exoplanet was pretty far fetched.

      • by tompaulco (629533)
        The more time passes, the more it's hard not to look at Drake's equation and figure that he might have been onto something ... if there's bazillions of planets, and a good chunk of those have moons, and a couple of those are in a habitable section ... well, maybe it's possible that there is far more life in the universe than we've previously thought.
        Well, according to the definition of life, planets are already life anyway, just not self-replicating life, and probably not intelligent.
        Me, I think the SETI
        • by gstoddart (321705)

          Well, according to the definition of life, planets are already life anyway, just not self-replicating life, and probably not intelligent.

          By what definition of 'life' is a planet 'alive'?? None that I've heard.

          Me, I think the SETI guys are closed minded. They are always on about "habitable planets". What they are really getting at is habitable by US. An extraterrestrial life form may have developed without the need for water, oxygen, and our temperature range.

          No, they're restricting their search to actual s

        • While I agree with you and also see the analogies between electrons orbiting in atoms clustered to form cells, and planets, stars and galaxies and wonder, I don't think it's fair to call the SETI guys closed minded for not. You are basically espousing fantasy, not open-mindedness. The speed of light is fundamental, and so is information theory. You can't have intelligent life the size of an electron, there isn't anywhere for their intelligence to be stored. An alien the size of the universe would be

      • Because, the default position has been that life is exceedingly difficult to make happen, and that you needed a truck-load of favorable conditions to even hope it could happen. I think the notion was that we were a rare and unique solar system. ...
        The more time passes, the more it's hard not to look at Drake's equation and figure that he might have been onto something

        For any denominator in Drake's equation where we don't have the technology to measure it, shouldn't the null hypothesis be that Earth (and by

  • by Anonymous Coward on Tuesday May 31, 2011 @12:22PM (#36298244)

    Don't tides and seismic activity play big roles in how we think life evolved?

  • Please explain (Score:5, Interesting)

    by truthsearch (249536) on Tuesday May 31, 2011 @12:25PM (#36298274) Homepage Journal

    Why was there ever an assumption that a moon is required for complex life? Stabilization of the axis and climate regions? Or did we just assume it because it worked here?

    • by gstoddart (321705)

      Why was there ever an assumption that a moon is required for complex life? Stabilization of the axis and climate regions? Or did we just assume it because it worked here?

      As I recall, the moon itself protects the planet from some amount of meteors and asteroids. Might reduce the chances of life getting wiped out too early.

      And, I think that the tides provided by a moon would keep things moving around instead of stagnating.

      Those are my best guesses from memory.

      • Re:Please explain (Score:4, Interesting)

        by VortexCortex (1117377) <VortexCortex AT ... trograde DOT com> on Tuesday May 31, 2011 @02:08PM (#36299722)

        And, I think that the tides provided by a moon would keep things moving around instead of stagnating.

        Not to mention the tidal forces make the Earth's surface flex about 1ft (as evidenced by my GPS) per day. All that flexing keeps the insides hot as well as triggers earthquakes that would otherwise be more devastating, and helps lava flow so that smaller, more frequent volcanic outbursts occur instead of less frequent super volcanic activities that would extinct us all.

        Conversely, why the hell we think only land life would be sentient and capable of technology is beyond me -- Seems that artificial water filled environments might be easier to maintain in space too (holds heat better, freezes at the edges for insulation, shields against certain UV wavelengths... There's a reason life happened in the watter first, making it to land doesn't seem all that important to me. Dolphins may actually be close to sentience -- they returned to the water because land life was harsh.

    • On all of your points.

      According to TFA we did assume based on some calculations from 1993 that "Without the moon, gravitational perturbations from other planets...would greatly disturb Earthâ(TM)s axial tilt".
      And as with all other assumptions we ever made on extraterrestrial life - if it worked here...

      There IS though, another point in the "moon equation" that is only hinted at in the article. Possibly cause it is assumed to be taken for granted (more of the "if it worked here...").

      That would leave ample time for advanced land life to evolve under relatively stable climatic conditionsâ"although what would happen to such life during an axial shift remains unclear.

      If you want your sea-

      • by arisvega (1414195)

        If you want your sea-dwelling life to migrate to land, stable yet powerful tides that regularly wash the aforementioned sea-dwelling life ashore surely are a plus. For plants and for animals that would feed on them.

        I think you got it backwards; life started in the sea, so there would be nobody to feed upon the first creatures that were washed and/or moved ashore.

        Plants went ashore to avoid being grazed upon, then followed the grazers to graze without competition and without being preyed upon, and the predators were last to follow to prey upon forementioned grazers without competition in those new hunting grounds.

        Plus, the buffer zone exists anyway because oceans are turbulent- my guess is tides would not be that cruc

        • by denzacar (181829)

          Plants went ashore to avoid being grazed upon

          Unless you are talking about triffids, plants didn't go anywhere - by themselves, that is. They were washed ashore and they multiplied from there.
          Also, being that they tend to be stationary plants don't really "avoid being grazed upon". Most of them actually count on it for procreation.
          Those that do develop defenses again mostly do that in a passive way - thorns, poisons, hard protective bark, resilience, quick procreation...

          What I'm trying to say is - plants are not really that pro-active. BUT... they DO h

    • Tidal forces are a big part of it. Both with the sea and with the liquid mantle. Before life at thermal vents was discovered, tidal pools were the chief candidates for the environment where life first evolved. They are a convenient interface between the sea, land and atmosphere. With no moon, there would be no tidal pools. Tidal interaction with the mantle is complex, but it may be the reason we have a strong magnetic field, unlike Mars or Venus.
      • by slyborg (524607)

        http://en.wikipedia.org/wiki/Dynamo_theory [wikipedia.org]

        Tidal interaction has nothing to do with it. Actually, the Earth's magnetic field would likely be stronger without the Moon since tidal interactions have transferred angular momentum to the Moon and slowed the Earth's spin over geologic time.

        Mars' core has likely long solidified given its small size and Venus rotates very slowly, which is why neither of them has a significant active dynamo.

    • by SETIGuy (33768)
      Yes, axis stabilization. But I don't know who ever believed it was a requirement. Planets in our solar system without large moons appear to have fairly stable axes.
  • I'm not an astrophysicist, so I'm a bit behind here, but how could the earth have collided with a Mars-sized object? Wouldn't it have caused the orbit to be much more eccentric than it is now?
    • This theory bothers me as well, but more for the simpler perspective of how the hell did the chuck of rock knocked off earth become so round in space? Shouldn't it be more like a big jaggiedy piece? It's not like it would weather down to a nice nice round object up there.
      • by julesh (229690)

        This theory bothers me as well, but more for the simpler perspective of how the hell did the chuck of rock knocked off earth become so round in space? Shouldn't it be more like a big jaggiedy piece?

        No. Gravity of any sufficiently large object causes it to become spherical over time.

      • This theory bothers me as well, but more for the simpler perspective of how the hell did the chuck of rock knocked off earth become so round in space? Shouldn't it be more like a big jaggiedy piece? It's not like it would weather down to a nice nice round object up there.

        Because when something like Mars hits something like the Earth, they tend to become molten from the energies involved and gravity does the rest. I believe this is one of the things pointing in favor of the big impact theory. Trips to the mo

  • by ShooterNeo (555040) on Tuesday May 31, 2011 @12:34PM (#36298400)

    Here's what a rational, realistic analysis of tech progression would expect. GIVEN that life on earth can self replicate itself and use a huge range of molecules for fuel, it seems obvious that more sophisticated life is possible than already exists. Our star exhausts enormous amounts of free energy into space every second. Thus, one would expect that some day, perhaps next century or thousands of years from now, we will develop more sophisticated life that can use ALL of the matter in our solar system (rather than just a narrow range in the biosphere) and will use solar energy to rapidly convert all matter into parts of this life. This expectation is known as the singularity, and generally is assumed to require both artificial intelligence and molecular manufacturing (nanotechnology) to take place. There are plausible reasons to think that this event might happen in this century.

    Well, if this is GOING to happen, and one would expect other intelligent life to do the same, and to eventually reach the same point. Then why don't we see the evidence of this out in space? Most of the stars should be missing, radiating mostly in the infrared. There should be a cacophony of data transmission between stars, although we might not be able to detect this. There should be other evidence of lively interstellar civilizations.

    Theories :
                    1. The singularity is not physically possible. That means, of course, that our theories of physics are massively wrong as well, and that all our assumptions about intelligent life are as well.
                    2. Every single intelligent civilization self destructs. This also seems ludicrous...even if it happens some times, there should at least be remnants.
                    3. We are the first within our region of space. It took life on this planet ~3 billion years to get to this point, and many billions of years for this planet to form with the elements it has. The universe is only ~13 billion years old. Possible...
                  4. Technology can do even more than we assume. Maybe you don't actually need to surround stars with solar collectors to get energy...And our neighbors obey the prime directive...

    And so forth. The number of possible theories is infinite, the number of probable theories large.

    • by Arlet (29997)

      2. Every single intelligent civilization self destructs. This also seems ludicrous...even if it happens some times, there should at least be remnants.

      We've had already two dozen civilizations on earth that self-destructed, so this seems like a likely scenario. The remnants are likely too hard to detect. Our current civilization is pretty much undetectable beyond the orbit of Pluto, and is probably already past its peak.

      • by Patch86 (1465427)

        2. Every single intelligent civilization self destructs. This also seems ludicrous...even if it happens some times, there should at least be remnants.

        We've had already two dozen civilizations on earth that self-destructed, so this seems like a likely scenario. The remnants are likely too hard to detect. Our current civilization is pretty much undetectable beyond the orbit of Pluto, and is probably already past its peak.

        Depends on your definition of civilization. If you take "Rome" as a civilization, sure it collapsed. But if you take "Humanity" as the civilization, it has never collapsed- just gone from strength to strength, occasionally with a new guy on top.

        If we found an alien civilization, I doubt you'd hear anyone saying "Wow, we've found the planet of the Gilgargiangan civilization; it's a real shame that the Flofringian civilization already died out due to barbarian invasion, that would have been way better".

        And I'

        • by Arlet (29997)

          And I'm not sure why you think our civilization is past its peak

          We're running out of cheap oil, and have nothing planned for its replacement that can be ready in time. Not even the Chinese.

          • Uhh..nuclear....

            I mean, it may be dirty, and it may have some nasty problems..but it DOES WORK. And there's more of it than we can use...

            • by Arlet (29997)

              Sure, but is it going to be ready in time ? Running cars on nukes will require lots of new reactors, a complete overhaul of the grid, better battery technology, and replacement of about a billion cars. Even if we knew what to do, how long would the implementation take ? Note that the nuclear option isn't very popular right now.

              • We have vast amounts of wealth, most of it we fritter on wars and entertainment. If energy prices went up 10 times, and our very survival was an issue, things would change very rapidly. Simple economics would dictate that...saving energy and batteries and a grid overhaul would all be cost effective if energy was expensive. Look at what happened during WW2 : the Axis powers developed novel methods to replace oil in a FEW YEARS WHILE BEING BOMBED.
                This is because they were desperate.

                We have a gigantic reser

      • by MaWeiTao (908546)

        Our current civilization is pretty much undetectable beyond the orbit of Pluto, and is probably already past its peak.

        You consider present-day civilization to be past it's peak? I'm really having a hard time comprehending why anyone would think this. I guess I don't understand what you mean by a self-destructed civilization. For me the collapse of human civilization means humans go extinct, or at least human population shrinks to such an extent that all progress comes to a halt and humanity reverts to a hun

        • by Arlet (29997)

          I mean "past its peak" in the sense that the dot com bubble was "past its peak" in 1999, even though the literal peak was in 2000. The last bit was just inertia.

          And I'm not talking about extinction, just the loss of radio technology for instance. Something that would make us completely undetectable as an intelligent life form viewed by somebody living a few light years away.

    • The singularity is actually a rather amorphous potential event for which there are many definitions, the complete use of a star's output is only one (and a rather arbitrarily grandiose one at that).

      I also don't think it naturally follows that a civilization's ultimate achievement is using stars. Stars are awesome and all, but couldn't there be a more efficient energy source than a huge blob of hydrogen fusing in the middle of space? I think there might be sources of energy heretofore barely imagined, like
    • by DM9290 (797337)

      Thus, one would expect that some day, perhaps next century or thousands of years from now, we will develop more sophisticated life that can use ALL of the matter in our solar system (rather than just a narrow range in the biosphere) and will use solar energy to rapidly convert all matter into parts of this life.

      why would one expect that?

      If the lifeform you vagely described evolved after N generations, you can't even begin to imagine what N-1 looks like. So even if we have 1,2,3,4,5,6 up to some finite generation which describes life on earth today, and even if we observe some trend towards efficiency (in fact we didn't.. but let that slide), without knowing how N-1 converts into N, or knowing for a fact that N-1 will automatically lead to N, then we have no rational expectation that N is inevitable, or even that

      • Because we have prototypes of this kind of life, and they work. (I am talking about the combined efforts of existing human beings and factories). Because anyone who builds high end versions of this would have an unbeatable economic and military advantage. Because once various examples of this kind of life exist, the ones that freely replicate to use all of the available resources will overwhelm the ones who do not.

    • by myrdos2 (989497)

      I strongly suspect that projects like interstellar colonization and Dyson spheres are theoretically possible, but that so far no intelligent species has ever managed it. It seems the simplest explanation by far. My theory is that advanced civilizations only last for a few centuries before they run out of metals. Or at least, that this is what will happen here on earth. See what you think: http://europe.theoildrum.com/node/3451 [theoildrum.com]

      It's possible that the answer to Fermi's Paradox is a depressing one...

      • That's ridiculous. Every atom (except for helium) we ever used in our civilization is still on this planet, somewhere. We get more energy falling for free on the planet every day than we have ever used. If we can't figure out a way to solve our problems given these resources, we deserve our fates.

  • 'There would be more then enough time' presumes you know what conditions are necessary for that time to start counting, Just because life started on earth at a specific time, does not mean every planet would have that event happen , if it ever, at the same point in planetary time line as it did on earth. there is no way to know if 'enough' would be normal when you can't explain IF little lone WHEN there is a start.

  • We have no fucking clue what it takes to support life as we know it, and we won't until we fully understand life and the process of abiogenesis. We do know a lot about where life cannot survive though, e.g. no oxygen, no water, etc. These equations are pretty much arbitrary.

  • This is just a computer simulation regarding the stabilization of the axial tilt. It doesn't take into account other contributions the moon would have on the development of life. Tidal forces, both with the ocean and the liquid mantle, are believed to have had a major contribution to the formation of life.
  • That's all very nice. When the scientist have found a representative number of worlds - what shall we say; 10? an even dozen? moonless, life-containing worlds, then they'll have a theory worth considering. Until then, they've got nothing.
  • That is just keep making it worse.
  • We're making an assumption that because it worked this way here, it can work this way elsewhere and the likelihood of life arriving under other conditions is unknown at best, and probably rather difficult. We have no basis for this assumption. It's in fact, equally likely that life arriving on earth was an extremely rare occurrence and that in most other situations it could have arrived much much earlier. For all we know even the planets in our own solar system could be swimming with life and we just haven
  • Tidal action certainly contributed to the evolution of aquatic creatures to land-based creatures, and without a large moon, tidal action is not as great. I didn't see this mentioned in the article. Am I overestimating lunar influence on tides?

  • I think this article understates the chance of life.

    First let me state that, to paraphrase an SMBC comic [smbc-comics.com] don't listen to people talking about something they are not an expert in.

    Second, rarely do the "you can't have life/intelligent life because..." people have both a biology degree and an astrophysics degree. You need both to make those kind of comments.

    Thirdly, we now just about jack-sh!t about the majority of the mass of the universe. Most mass is "dark matter", and of the stuff that isn't dark

  • Intelligent life may evolve differently, for example the dominant lifeform might be 3 legged with 2 heads and its brain in its belly.

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