Term
Declination
The angular position of the Sun north or south of the celestial equator, equivalent to the latitude of the subsolar point. It varies between about 23.44° north and south through the year and helps determine noon altitude and daylight duration.
What to look for
Meteosat-9 observed this day–night boundary on 21 December 2010. Earth's tilted axis puts the subsolar point south of the equator and gives southern latitudes longer days. Declination is the Sun's angle north or south of the equatorial plane; the tilt of the boundary is observational evidence, not an angle scale.
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