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I Orientation of the Earth, Sun and Solar System in the Milky Way

  1. Nov 2, 2017 #61


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    Haha. There are worse places on the Web, I know.
  2. Feb 28, 2018 #62
    Thanks for the great diagrams, working back through the traditional astronomical jargon was going to be tedious!
    Perhaps the diagram could be made less'busy' using an "exploded view" where the plane of the Earth-Moon system ,
    is shown as a smaller part of the plane of the Solar System , it self a smaller part of the plane of the Milky-Way !

    When I started googling "galactic co-ordinate system", my naive idea was for a co-ordinate system,
    with origin based on the multi-million solar-mass black-hole at the'centre' of the Milky-Way Galaxy (ie ours);
    Since the diameter of the event-horizon of this is less than the orbit of Jupiter ;
    it is effectively a point relative to the Milky-Way's diameter of 100x10^6 light-years.
    The natural co-ordinate system which suggested itself was actually a cylindrical one with the our star (Sol ?)'s;
    distance to that centre as one co-ordinate, it's hieght above or below the galactic plane (or angle subtended at the origin) another;
    and finally the whole co-ordinate system rotating with the Milky-Way by setting Sol's 'longitude' to zero degrees !
    Perhaps I have been unconsciously influenced by "Star-Trek" with it's 'alpha-quadrant' etc ?
    regards Rohan
    Last edited by a moderator: Feb 28, 2018
  3. Feb 28, 2018 #63


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    Unfortunately the location of the exact center of the Milky Way is not known due to a number of issues. From wiki:

    An accurate determination of the distance to the Galactic Center as established from variable stars (e.g. RR Lyrae variables) or standard candles (e.g. red-clump stars) is hindered by countless effects, which include: an ambiguous reddening law; a bias for smaller values of the distance to the Galactic Center because of a preferential sampling of stars toward the near side of the Galactic bulge owing to interstellar extinction; and an uncertainty in characterizing how a mean distance to a group of variable stars found in the direction of the Galactic bulge relates to the distance to the Galactic Center.

    The supermassive black hole is almost certainly not at the center though, but probably lies a few thousand light-years off from the center. It's a bit like how the Sun isn't always the center of the solar system (as defined as the barycenter, or center of mass).
  4. Feb 28, 2018 #64
    That 3D TV & Film never really worked out - at least in its latest iteration - is a topic beyond the scope of this thread. Nevertheless, it would be an ideal way to represent the orientation (and motion) of the solar system in relation to the Milky Way, especially if it included 'zoom' controls. Such a fully immersive apprehension-at-a-glance technology will probably be a visual treat reserved for the next generation. Saying that, I did once undertake a slow tour of the solar system via Oculus VR, and that was tremendously impressive. Sticks in the memory, even now.
  5. Feb 28, 2018 #65
    I made this diagram using the drawing tools Microsoft Word believe it or not. The reason I made it was to avoid using a lot of words, which wouldn’t really give people a clear idea idea of what I was trying to convey. And in all honesty, I don’t really understand what you’re saying. I would suggest, if you’re trying to get your idea across, that you use pictures and drawings (worth thousands of words).
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