Essen, horizontal view

Internet Project

Observing, Photographing and Evaluating the

Transit of Venus, June 8th, 2004

Essen, equatorial view


  1. Determing the radius of Venus' orbit by position measurements on the day of transit and on one additional day during the retrograde motion

    1. On June 8th, during the transit Venus has the following position:
    2. On June 28th, the position of Venus is:
    3. During those 20 days, Venus, therefore, has apparently moved by
    4. During that time interval, Earth and Venus have passed the following central angles:
    5. Taking these results together, we find the following radius of Venus' orbit:

  2. Determing the radius of Venus' orbit by two position measurements two days during the retrograde motion

    Suppose you have measured Venus' position on May 23th, instead of June 8th:

    Then, the numerical determined zero of the above function is:
    From this value follows the same radius as in the above example.

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Prof. Dr. Udo Backhaus
last modification:  March 28th, 2008