The summer solstice also called the midsummer, occurs when one of Earth's poles has its maximum tilt toward the Sun. It happens twice yearly, once in each hemisphere (Northern and Southern). For that hemisphere, the summer solstice is the day with the longest period of daylight and the shortest night of the year, when the Sun is at its highest position in the sky.
What happens during the summer solstice?
At the summer solstice, the Sun travels the longest path through the sky, and that day, therefore, has the most daylight. When the summer solstice happens in the Northern Hemisphere, the North Pole is tilted about 23.4° (23°27´) toward the Sun. Because the Sun’s rays are shifted northward from the Equator by the same amount, the vertical noon rays are directly overhead at the Tropic of Cancer (23°27´ N).
Six months later, the South Pole is inclined about 23.4° toward the Sun. On this day of the summer solstice in the Southern Hemisphere, the Sun’s vertical overhead rays progress to their southernmost position, the Tropic of Capricorn (23°27´ S).
The significance given to the summer solstice has varied among cultures, but most recognize the event in some way with holidays, festivals, and rituals around that time with themes of religion or fertility. For example, in Sweden, midsummer is one of the year's major holidays when the country closes down as much as during Christmas.
In some regions, the summer solstice is seen as the beginning of summer and the end of spring. In other cultural conventions, the solstice occurs during summer.
Solstice is derived from the Latin words sol (Sun) and sistere (to stand still).