I've been trying to wrap my head around this problem for the last few hours. I have very little math experience so if I could get some help with this it would be great.

The issue is that I've found many problems that claim to give the solar declination. Problem is that when ever I use these equations to find the declination at the equinox the number is not 0. Also the numbers don't seem to follow a slow curved descent or ascent from the highest point 23.45 degrees to the sun's lowest point -23.45. I'm sure the equations are correct and I am doing something wrong. Or interpreting them incorrectly. Here is a website I used

http://www.usc.edu/dept-00/dept/archite ... basic.html

The equation there is:

Declination is calculated with the following formula:

d = 23.45 * sin [360 / 365 * (284 + N)]

Where:

d = declination

N = day number, January 1 = day 1

But if I plug in 81 for N (which is the sping equinox) I get 22.48. I would expect to get 0.

Thanks for any help.