Solstice, an event that occur twice a year, where the Sun appears to reach its northern most or farthest point from an observer on earth or southern most or the closest point from an observer on earth. The Summer Solstice is the longest day of the year, and happens around 21 December in the Southern Hemisphere and 21 June in the Northern Hemisphere. The WInter Solstice is the shortest day of the year, and happens around 21 June in the Southern Hemisphere and 21 December in the Northen Hemisphere. The exact date of each solstice changes by a few days each year, the orbital and rotational motion of the earth such as ‘wobble” in the Earth’s axis also contribute to the changing solstice dates. The solstices occur because the rotation axis of the Earth is tilted by an angle of 23.5 degrees from the vertical. If the Earth’s rotation was at right angles to the plane of its orbit around the Sun, there would be no solstice days and no seasons. The number of daylight hours received on each solistice directly corresponds to the distance of the observer on earth from the sun.