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Calculating sunrise/sunset times

  1. Jul 11, 2015 #1
    I'm not sure if this is in the right forum but I assume someone in charge can move move it if it's not. Anyway, is there an equation or algorithm or something I can use to calculate the sunrise/sunset times at a given latitude/longitude on a given day of the year (or possibly something that would give me declination so I can put zero in and solve)? I know the basics of how it works (more extreme day lengths around the solstices and at higher latitudes and the sun not rising/setting at particularly high latitudes around the solstices, etc.) but I was wondering if there was a mathematical way to figure it out. I'm also aware that there are other things that go into it but I just need what I mentioned for my purposes.
  2. jcsd
  3. Jul 12, 2015 #2


    Staff: Mentor

  4. Aug 3, 2015 #3
    While this is going, I can give this equation which tells where ( angle ) the Sun rises ( or sets ), north or south of due East ( or west).
    sin D = cos L sin ( ANGLE )
    D= declination L=latitude
    Now we have the when and where.
  5. Aug 3, 2015 #4
    Petter Duffett-Smith wrote a book, Practical Astronomy With Your Calculator which includes algorithms for calculating sunrise and sunset, and many other astronomical events. A later version with co-author Jonathan Zwart includes instructions on using spreadsheets to calculate events. I used the former version several decades ago to write programs in Basic. It was entertaining then, archaic today, but the logic is the same.
  6. Aug 7, 2015 #5
    Or look up the works of Jean Meeus. He's written several books on astronomical calculation.
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