What is the declination of the sun ?

Question

i thought is should be 0 but is isn't on the google sky program

Answer 1

Declination is measured relative to the Earth's equatorial plane:

http://en.wikipedia.org/wiki/Equatorial_...

Since the axis of the earth is at 23 degrees from being perpendicular to the plane of the ecliptic (the plane that includes the Sun and the earth, the declination of the Sun varies with the seasons, being higher in summer and lower in winter.

In particular, the declination d is approximately:

d = -23.45 + cos((360/365)(N + 10))

where N is the number of days since january 1 and all angles are in degrees. Wikipedia also has a more accurate formula:

http://en.wikipedia.org/wiki/Declination