<P> On the equator, the sun will be straight overhead and a vertical stick will cast no shadow at solar noon on the equinoxes . On the vernal equinox, north of the subsolar point (on the equator) the vertical stick's shadow will point a little westwards of true north (NNW) reading 336.5 ° from true north and little eastwards of true south (SSE) reading 156.5 ° from true north . On the autumnal equinox, north of the subsolar point (on the equator), the shadow will point a little eastwards of true north (NNE) reading 23.5 ° from true north (and south of the subsolar, the shadow will point a little westward of true south (SSW) reading 203.5 ° from true north). </P> <P> The same stick will cast no shadow on the summer solstice in the Northern Hemisphere when the subsolar point is on the Tropic of Cancer 23.44 ° north of equator . Although north of 23.44 ° N the shadow will point towards true north and south of 23.44 ° N the shadow will point towards true south . The reverse occurs on the winter solstice in the Northern Hemisphere when the subsolar point will be on the Tropic of Capricorn 23.44 ° S and a vertical stick will cast no shadow along that point . But north of the Tropic of Capricorn solar noon shadows will point towards true north and south of the Tropic of Capricorn shadows will point towards true south . </P> <P> The solar noon shadows of objects on points beyond and below subsolar points will point towards true north and true south respectively only when the solar declination has its maximum positive (δ ☉ = + 23.44 °) or maximum negative (δ ☉ = − 23.44 °) value . On the other hand, on the equinoxes when the sun is neither declined north nor south (δ ☉ = 0 °) and solar time noon shadows point NNW north of the equator and SSE south of the equator on the vernal equinox (and point NNE north of the equator and SSW south of the equator on the autumnal equinox). </P> <P> North of the Arctic circle and south of the Antarctic circle, there will be at least one day a year when the sun is not above the horizon for 24 hours during the winter solstice, and at least one day when the sun is above the horizon for 24 hours during the summer solstice . </P>

When is the declination of the sun moving south