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Space Earth Science

Milky Way's Spiral Arms Could Not Have Caused Climate Change 86

Posted by Soulskill
from the it-was-the-one-armed-galaxy dept.
KentuckyFC writes "One of the puzzles of Earth's climate history is an apparent 140-million-year cycle in the climate record. Various astronomers think this can be explained by the passage of the Sun through the spiral arms of the Milky Way, which also seems to have had a period of about 140 million years. The thinking is that in regions of denser star populations, supernovas would have been more common, bathing the Earth in cosmic rays more often. These cosmic rays would then have seeded the formation of clouds that cool the planet. But in recent years, astronomers have mapped out the structure of the galaxy in much more detail. And now a pair of US astronomers have reanalyzed this climate change idea in light of the new evidence. Their conclusion is that the climate change cycle cannot possibly have coincided with the movement of the Sun through the spiral arms. So whatever caused the 140-million-year climate change cycle on Earth, it wasn't the Sun's passage through the galaxy."
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Milky Way's Spiral Arms Could Not Have Caused Climate Change

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  • by HerculesMO (693085) on Friday June 26, 2009 @08:31PM (#28490489)

    Because now the political "we don't cause GW" arguments will begin, and the bickering....

    It shouldn't even be about global warming. It should be about national security. If you have no renewable resources, and rely on other (enemy) nations to provide that stuff to you and your way of life, you have a severe problem.

    Let's get off oil if for nothing else, to bankrupt every middle eastern country out there. We won't bother maintaining a presence there if there's nothing to take advantage of.

    • by eln (21727) on Friday June 26, 2009 @08:40PM (#28490557) Homepage
      It needs to be at least a little about the environment, because otherwise our easiest move may be to switch from oil to coal, which we have a lot more of. Of course, coal pollutes like crazy (even so-called "clean" coal), so it would be nice if we could keep the environmental stuff at the forefront too. I do agree that national security is a helpful selling point, though.
    • Let's get off oil if for nothing else, to bankrupt every middle eastern country out there.

      On the other hand, the only middle eastern countries that don't want to nuke the US to hell are those which are rich off oil.

      • Re: (Score:2, Insightful)

        by HerculesMO (693085)

        Uhm, the countries that have oil and we buy it from them don't want to nuke us.

        The ones we take oil from do want to nuke us.

        Either way, if we remove oil from the picture, it's a win-win.

        • by R2.0 (532027)

          Where, exactly, does Iran fit into your perfectly classified view of oil and nuclear politics?

        • by ScentCone (795499) on Friday June 26, 2009 @10:24PM (#28491061)
          The ones we take oil from do want to nuke us.

          Please list the countries from which we "take" oil.
          • by abigor (540274) on Friday June 26, 2009 @11:08PM (#28491245)

            Exactly. The people who rattle on about how the US invades countries for oil tend to fall silent when they find out that Canada is the largest exporter of oil to the US.

            • Re: (Score:2, Insightful)

              by chartreuse (16508)

              Nice straw man. Time to learn about realpolitik.

            • Re: (Score:1, Insightful)

              by Anonymous Coward

              It's not about where in particular the US consumer's oil comes from, since it's all part of a single global market.

              What's important, in geopolitical terms, is controlling the oil that other people are using. It gives tremendous political leverage internationally. This has almost nothing to do with domestic US politics.

              Consider for instance how FDR would have gotten the USA into WWII, without having an effective monopoly control over global oil sales (in cooperation with the British and Dutch govt. in exile

              • by Chris Burke (6130)

                It's not about where in particular the US consumer's oil comes from, since it's all part of a single global market.

                What's important, in geopolitical terms, is controlling the oil that other people are using. It gives tremendous political leverage internationally. This has almost nothing to do with domestic US politics.

                Thanks. People go on about how oil is a fungible commodity, as if that means there's no profit or advantage in owning or controlling sources of it and that therefore the U.S. (and I guess no

            • by Lars T. (470328)

              Exactly. The people who rattle on about how the US invades countries for oil tend to fall silent when they find out that Canada is the largest exporter of oil to the US.

              Let's ignore that Canada still only supplies 9% of the oil the US consumes. It never was about oil for Americans, it was always about oil for American oil companies.

              • by abigor (540274)

                Fair enough, though "American oil companies" is still misleading, as Shell's behaviour in Nigeria demonstrates. Given the chance, large corporations from anywhere often behave poorly.

                I am no huge supporter of oil corporations, believe me. But I do get tired of the monomaniacal obsession with demonstrating how evil the US is in all things. It is frustrating to meet people who honestly believe that the US "steals" all of its oil.

                By the way, Canada supplies about 23% of US petroleum, and 22% of crude oil, not

    • Re: (Score:2, Informative)

      by larry bagina (561269)

      Where is the national security in forcing any remaining manufacturers offshore where they don't have to deal with carbon credits and higher electrical costs?

      The US has 273 billion tons of proven coal reserves, far more than any other country, and that coal can be liquefactioned into gasoline.

      • Re: (Score:1, Interesting)

        by HerculesMO (693085)

        Again, FINITE RESOURCE.

        Coal isn't renewable. That's kind of the point. We will just be down the same path and the same ultimate consequences at a more accelerated rate. You are thiinking on the span of what, maybe 50, 100 years? I am thinking a bit longer term.

        • by Dr Damage I (692789) on Friday June 26, 2009 @11:52PM (#28491637) Journal
          Long term thinking is all very well so long as the short term picture doesn't sneak up and slit your throat before you get there. We can't "get off oil" tomorrow, that would achieve much the same effect as carpet bombing Americas 20 biggest cities would have. Until there is a viable long term alternative to fossil fuels for baseload electrical power, heating, cooking and transportation, it makes sense to pursue short term solutions to energy problems at the same time is we pursue long term renewable sources of energy
          • Re: (Score:3, Insightful)

            by john.r.strohm (586791)

            Dude, there already *IS* a viable long term alternative to fossil fuels for baseload electrical power, heating, cooking and transportation.

            It is called "nuclear".

            See "The Economics of Nuclear Power" at http://www.world-nuclear.org/info/inf02.html [world-nuclear.org].

            For the people who feel like ranting about nuclear waste, consider the sheer size of the installations that are being proposed for ground-level solar arrays or algae farms, and ask yourselves how many Astrodome-sized nuclear waste storage facilities could be built

      • by BlueStrat (756137)

        Where is the national security in forcing any remaining manufacturers offshore where they don't have to deal with carbon credits and higher electrical costs?

        That's the elephant in the room that they don't want anyone to notice. Once the cap & tax hits, any business that can leave, will. Those that can't will raise their prices to consumers and if unable to maintain sufficient sales because nobody will be able to afford to buy anything, they will fail and disappear. These price increases will include ev

    • by khallow (566160)

      Let's get off oil if for nothing else, to bankrupt every middle eastern country out there.

      Suppose I don't care to bankrupt myself in order to bankrupt every Middle Eastern country out there? And how does destroying the US economy help national security? Frankly, the current situation isn't that bad to warrant such action.

  • Heh (Score:5, Funny)

    by Kingrames (858416) on Friday June 26, 2009 @08:32PM (#28490497)
    This is the very technical (and long-winded) explanation for something along the lines of "We are telling you, Miss Daisy, that your cat was not put into that tree by giant ninja robots from outer space."
    • Re: (Score:3, Interesting)

      by interkin3tic (1469267)

      Unfortunately, Miss Daisy will still cite it as one of the many reasons she shouldn't have to keep her damn cat inside.

  • I took a look at it: http://arxiv.org/abs/0906.2777 [arxiv.org]

    They're jumping to conclusions. It will be 140 million years before we have enough data to decide.

  • It must be the unicorns fault!

    I mean... it cant be us. Right?
  • Decepticons (Score:1, Offtopic)

    by tverbeek (457094)
    My theory is that the Decepticons are responsible.




    (Sorry, but my brain is still recovering from the 2.5-hour Mighty Transformin' Power Rangers movie I sat through as a favor for my friend who wanted to see it. The dramatic parts made me laugh, the action scenes nearly put me sleep, and the comedy bits made me wish my phone would ring.)
    • Does your friend have a mental disability (includes being under the age of 12)? If so, well, you're a better friend than I. If not...you need to redefine "friend."

  • I have a hunch that the scientist that first theorized this prefaced it with "Good news, everyone!"
  • by ctrl-alt-canc (977108) on Friday June 26, 2009 @09:08PM (#28490677)
    Both Shaviv's and Melott's papers are based upon models of the Milky Way that are built from observations taken from a single point in the universe, and made during a negligible time frame. This model is then kept valid and unchanged for a timeframe of about 1.000.000.000 years, neglecting for example errors in measuring accelerations of the galaxy and of the solar system, the 3D structure of the galaxy, dark matter influence (and existence...) on the motion of the galaxy, etc. Still too much unknowns before reaching a definite answer, isn't it ?!?
    • But you've now lost all correlation between the two cycles, which was the driving force for the hypothesis. Scientifically, this is like suspecting someone of a murder solely because an eyewitness placed him at the crime; proving the eyewitness was mistaken; then, insisting he could still be the murderer because no one has proven he wasn't there. I mean, sure, that's technically true, but it's not a very promising lead anymore, is it? Going back to the science, to support the original hypothesis you'd pr
      • Re: (Score:2, Interesting)

        by ctrl-alt-canc (977108)
        Here [ucsd.edu] you can find a brief description of the Milky Way structure. In the time frame of 1 Gy our solar system makes probably four revolutions around the center of our galaxy. I try to make an example about what is the problem with the theory related with TFA. Suppose you live in New York City: get out from your home, look carefully to people around you, then get into the underground. Make four trips all around the city, and go back home. Are the very same people you met before still all around you ?!? Some o
  • A lot of the invalidations of these spaced theories tend to focus on the effects of cloud formation by cosmic rays, but are they so sure that these are the only effects that space could have? Space is pretty big, and the earth is pretty complex, and I would be willing to bet that there's going to be something out there in space, besides the obvious asteroid, that screws us.

    • Agreed, there are too many unknowns and no theory is provable. However TFA does a credible job of dismissing a group of theories from further consideration, so it is significant in narrowing things down a little bit.

      This wikipedia article on the galaxy [wikipedia.org] seems like a good overview of known data; a long article but well worth the reading, as recent observations have caused major changes to the model of the Galaxy a lot of us grew up with. The specific section I'm pointing to describes how Sol bobs from one

  • Not Arms (Score:3, Interesting)

    by DynaSoar (714234) on Saturday June 27, 2009 @02:10AM (#28492503) Journal

    In 1978 is was suggested that a galactic density wave, rather than passage through the arms, was responsible for the 140 My events. This wave, with a period 1/2 that of galactic rotation, eminates from the galactic core. http://www.springerlink.com/content/k1t6v868227t7403/ [springerlink.com]

    The solar system doesn't just orbit the galaxy. It oscillates up and down through the galactic plane with a period of 88 +/- 5 My. This too has been suggested as being involved in extinctions, since the galactic plane is denser than the regions outside it.

    I'm glad they got a better galactic map, and I'm sure it shows what they say. But the arms themselves aren't the only things hypothesized to be involved.

    • Re:Not Arms (Score:4, Interesting)

      by Teancum (67324) <robert_horning@n ... minus physicist> on Saturday June 27, 2009 @07:33AM (#28493915) Homepage Journal

      One of the problems with the suggestion of moving through the galactic plane being a major issue is that the Sun is currently very close to the main galactic plane at the moment. That is something that has to be explained if you want to use this concept to prove or disprove a hypothesis regarding the orbit our solar system takes through the galaxy.

      What I would be curious about is the "CO2 data" that they are using, and the assumption that global temperatures have a direct correlation to this substance, not to mention the reliability of the measurement process over the scale of billions of years to calculate what levels of this gas were through more than just a couple of galactic years. Yes, I know there are attempts to measure global temperatures over time using the geologic record, but it seems to me that both the CO2 measurements as well as measurements of the orbit of the solar system have such huge margins of error that doing a statistical comparison of the two could give you virtually any kind of conclusion that you want.

      I have to assume that this paper addresses these issues in some detail (I would love to read the original paper).

      One other thing that struck me, in looking at the supposed solar system orbit that they plotted in this paper, is if they have accounted for the fact that the galaxy is a dynamic and not a static place? They calculated the path of the Sun over apparently three galactic years, but at the same time all of the objects that they used for measuring protuberance of the orbit are also moving in their own galactic orbits. If there is a model that they were able to develop that shows the galactic evolution of the Milky Way over the past 500 million years. Seriously, I had no idea that stellar parallax measurements (to accurately plot the positions of stars) were so accurate and have been for long enough to not only get a good fix on the position of a large number of stars in the Milky Way to be able to also plot the apparent trajectories of this many stars and galactic nebulae. That is some trick, and such a model would have a great many other uses besides trying to prove anthropogenic global warming (or disproving an alternative hypothesis).

      My understanding was that stellar parallax measurements were only good to about 1 or 2 significant digits and getting the order of magnitude down. That may have improved with the Hubble and some other star surveys with really accurate telescopes, but I don't think it is too much better than that.

      • by DynaSoar (714234)

        A very coherent and insightful reply. Thank you.

        The original paper re: galactic plane crossing is available at http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=1851772 [cambridge.org] but it costs US$20.

        Being close to the galactic plane now may or may not be a significant threat if the density wave theory were also correct. It may be that they need to coincide for there to be enough matter density to initiate an event.

        Something I don't believe any of the references considered was that the sun an

    • by Thelasko (1196535)

      This too has been suggested as being involved in extinctions, since the galactic plane is denser than the regions outside it.

      One of the theories that makes sense to me is the increased chances for asteroid strike. This paper doesn't seem to touch on that.

  • The actual cause of global warming, is a planet in the solar system that Nasa warned us about in 1983 (Washington Post) but was quickly repressed by the Government. Since then, the planet has progressed in it's sling orbit through our solar system. Currently, it resides just north of the Sun's south pole near the ecliptic. It's a magnetic brown dwarf with unusual moon swirls in 2 "tails", which is why ancient cultures depicted it as a winged planet. It's a magnetic powerhouse, which is why the Sun is un
    • So the sunspots have returned, where's your god, er, magnetic planet now?

      Care to explain how EVERY observatory, especially those not under United States governmental control, would be even remotely willing to suppress this information?

      However, that said, if you really believe this, can I buy your house/car/stereo for a dollar? I mean you won't have any use for it in a few months if you're right so put your money where your mouth is.

  • The actual cause of global warming, is a planet in the solar system that Nasa warned us about in 1983 (Washington Post) the news of which was quickly repressed by the U.S. Government. Since then, the planet has progressed in it's sling orbit through our solar system. Currently, it resides just north of the Sun's south pole near the ecliptic. It's a magnetic brown dwarf with unusual moon swirls in 2 "tails", which is why ancient cultures depicted it as a winged planet. It's a magnetic powerhouse, which i

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