What happens at a solstice?
The solstice takes place twice a year. In the northern hemisphere the summer solstice takes place in June and the winter solstice in December, in the southern hemisphere it is the other way round. In the course of a year, the sun reaches once the largest distance north and once the largest distance south of the celestial equator. Afterwards it seems to approach the celestial equator again on the ecliptic line.
On the day of the summer solstice, the sun reaches its peak above the horizon at noon and the days become shorter again. On the day of the winter solstice the opposite happens - at noon the sun is at its lowest position above the horizon. The dates, together with the Equinox, determine the astronomical seasons.
Some cultures celebrate the day of the summer solstice with secular or religious festivities. The winter solstice was an important festival in many ancient and early medieval cultures.