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Distance to the Sun using Venus transit

  1. Sep 3, 2013 #1

    I was wondering if anyone of you know how to calculate the astronomical unit 1 AU, using data from a Venus transit and not using the parallax method. I already have all the data from the 2012 transit; the time it was in phase 1 when it contacts the Sun's disk and when it leaves the disk in phase 4 etc. The latitudes are all included. I haven't found anything helpful yet. So, if you have any idea or maybe a website that explains how to calculate this without the parallax method, please help.

  2. jcsd
  3. Sep 3, 2013 #2


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    This link has a clear elementary explanation of Halley's method proposed in 1716.


    However this seems to be what you call the "parallax method" because it involves timing the same transit as seen from different locations on earth, essentially from different latitudes.

    If you would like to help me understand what you are looking for (and help others in the same situation who might read the thread) you could be more explicit. Are you in fact looking for a method that does not involve making TWO separate observations of the same transit, from different latitudes on earth?
    Are you looking for a method to find the AU from just your one observation?
    I have a vague memory of having examined a calculation scheme of that type, but I'm not sure how it worked, someone else might know though.
    Last edited: Sep 3, 2013
  4. Sep 3, 2013 #3
    That's right, I'm searching for a method that does not involve making TWO separate observations of the same transit.
  5. Sep 4, 2013 #4
    How can you calculate is when there is an angle between the Venus transit, seen from us? Imagine the Sun, with Venus being a black dot. One of the dots are on the center of the Sun and the other slightly to the left in an angle under it. How should I consider this during my calculations? :S
    Last edited: Sep 4, 2013
  6. Sep 6, 2013 #5


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    I don't think there's another way other than parallax.
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