Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Galaxy orbit

  1. Aug 21, 2005 #1
    Something important to think about:
    If it takes us between 225 and 240 millions years to make one Galaxy orbit wouldn’t it be prudent to associate magnetic polar shift, global warming, and ice-ages to where the sun was located when these events occurred? Were we close to or farther away from something which had an effect on our sun? Could events such as Continental drift/shift be a part of the equation? Something to think about.
    Bobby R. asks…J
  2. jcsd
  3. Aug 21, 2005 #2


    User Avatar
    Science Advisor

    Not really. The times between ice-ages, polar shift, global warming, etc. is considerably less than 225 million years.
  4. Aug 21, 2005 #3


    User Avatar
    Science Advisor

    It is my understanding that the particular phenomena you mentioned did not happen at regular intervals. However, mass extinctions do seem to occur at evenly spaced periods of opportunity, and the spacings roughly correlate to one half of a galactic orbit. This has given rise to the theory that mass extinctions are tiered by the perturbative effect of our solar system passing through the thickest part of the galactic disk (twice every orbit).
    Last edited: Aug 21, 2005
  5. Aug 21, 2005 #4


    User Avatar
    Science Advisor
    Gold Member

    It actually does it more than twice an orbit. I'm not sure of the dynamics, but its not the same as a planet passing through its ascending and descending nodes. The Sun bobs up and down more than this.
  6. Aug 23, 2005 #5
    There is not a simple answer. The variables seem to increase the more I read.
    Interestingly, our Sun oscillates in and out of the plane of the galaxy (up and down) every 70 million years (approx.). Which means we pass through the Galactic mid-plane about every 35 million years. The number of cosmic rays which hit the Earth increases during the near hundred thousand years we are closest to the Galactic plane. What happens to Earth’s temperature during this transition through the mid-plane? Could one assume influence on Earth’s magnetic field as well?
    Our Sun is located in a small spiral arm we call the Orion arm (or local arm) which is really a connection between the two nearest major spiral arms (Sagittarius and Perseus). We pass through a major spiral arm about every 100 million years taking about 10 million years to go through. During the transit, there would be a higher rate of ’nearby’ supernova and possible other ’environmental stresses’ which could alter the climate of Earth.
    Simply put, as our Solar System travels in Galactic orbit there are many potential stresses we can speculate ‘cause and effect’ from. Along with our Sun there are approx. 400 billion other celestial bodies in the Milky way.
  7. Aug 23, 2005 #6


    User Avatar
    Science Advisor

    There are some hypothesis that the passage through dense interstellar clouds could pertub the heliosphere increasing the production of anomalous cosmic rays which reach afterwards the inner of the solar system. These cosmic rays could lead to some chemical reactions on the earth’s atmosphere contributing to the dissociation of ozone and thus leading to an increase of the UV radiation from the sun that reaches the earth's surface. This radiation has an effect on the genetic code. Also, the passage through the most dense zone of the galatic plane could perturb Oort’s cloud leading to an increase in the number of comets traveling towards the inner solar system.

    I have no references about both at hand, but I am sure you can find about these in google (I remember to have read about both in press articles).
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook