4
$\begingroup$

I came by some graphs showing the declination for sun and moon (between angles of -30° and +30°). The graphs look very much like sine waves.

I googled a bit and read about what the declination is, and I found tools to look up the declination for a certain date. However, what I really haven't understood yet is, how to measure the declination. So if I would like to create such a graph during the next 365 days by hand, what exactly would I measure?

Improve this question
$\endgroup$
2
$\begingroup$

You'd wait till the sun was at the highest point in the sky for the day, and measure the angle it makes with the vertical.

Improve this answer
$\endgroup$
3
  • $\begingroup$ If you measure both parameters you can make a solar Analemma like the ancients: en.wikipedia.org/wiki/Analemma $\endgroup$ – user6972 Sep 7 '13 at 18:30
  • $\begingroup$ are there any tools to precisely measure the angle (is a sextant the right tool for that?) $\endgroup$ – navige Sep 8 '13 at 10:50
  • 1
    $\begingroup$ @navige: a sextant would definitely work. Make sure to have a filter on it so the sun doesn't blind you. $\endgroup$ – Jerry Schirmer Sep 8 '13 at 18:32
2
$\begingroup$

Plant a stick in the ground vertically (use a level). Length of shadow / length of pole = tan (declination).

Declination is the angle the sun makes with the zenith (direction pointing upwards--the stick's axis)

Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.