Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Sunrises and sunsets on the compass

  1. Apr 4, 2005 #1


    User Avatar
    Gold Member

    I feel a fool for even asking this; my father is a Geography teacher, and I am supposedly well-educated in the sciences.

    But the only dumb question is the one not asked, so...

    I've never quite understood where the Sun actually rises and sets on the compass. It does not set due West (except at brief, specific times of the year).

    If I live at 45N lat. then:
    - at summer solstice, the sun rise to within ~22.5d of zenith at noon
    - at summer dusk, the sun will not set due West, it will set at ~22.5d North of due west
    - in the peak of winter, the sun will only rise to within 67.5d of zenith at noon
    - at winter dusk, the sun will set 22.5d south of due west

    Are these suppositions correct?
  2. jcsd
  3. Apr 4, 2005 #2

    Your values are approximately correct for the height at noon. I believe the formula is (L-delta) where L is the latitude and delta is the angular distance of the sun above (or below) the equator. On summer solstice the result is (45-23.5) or 21.5 degrees from zenith, while for winter solstice it is (45+23.5) or 68.5 from zenith.

    However, these may not translate exactly into the north south deviations of the sun at sunrise and sunset. The equations may notbe linear in this manner. I am not sure. You can probably look them up on the web. They might be found by searching for solar altitude, declination, or azimuth.

    Try this site for tables.

    http://aa.usno.navy.mil/data/docs/AltAz.html [Broken]

    Last edited by a moderator: May 2, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook