Solstice
The moment in the northern hemisphere when the Sun attains its lowest declination of -23°26' (or -23°.44) with respect the equator plane. It happens when the Earth's axis is orientated directly away from the Sun, on 21 or 22 December. During the northern winter solstice the Sun appears to be directly overhead at noon for places situated at latitude 23.44 degrees south, known as the tropic of Capricorn. The winter solstice can occur at any moment during the day. Two successive winter solstices are shifted in time by about 6 h. The winter solstice in the northern hemisphere is the summer solstice in the southern hemisphere.
Winter solstice