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Parallax equation

  1. Nov 12, 2003 #1
    please can somebody help me with this parallax equation:

    D=distance to star
    using the rule D=(d/2)/tan(theta/2)
    when d = 300*10tothe6
    and theta = 5*10tothe-5

    what is the distance to the star in km and light years?
  2. jcsd
  3. Nov 12, 2003 #2

    Doc Al

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    Staff: Mentor

    What's the problem?

    (d is in what units?)
  4. Nov 12, 2003 #3
    d is in km and theta is in degrees.
    This is as close as i can get:
    for this answer i get a result of:


    So, is this answer the number of km?

    what is this answer in exponential form? ie: 34 * 10tothepower13?

    1 light year is 9.467*10tothepower12, so in light years i think the distance will be:
    27 light years

    Please let me know if i am right
  5. Nov 12, 2003 #4

    Doc Al

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    Staff: Mentor

    D and d have the same units. Your value for D in km is correct, but you messed up the conversion to light years. Do it over, more carefully.
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