Solstice
The June Solstice happens when the Northern Hemisphere of the Earth is tilted toward the Sun and the Southern Hemisphere of the Earth is tilted away from the Sun. At the North Pole, the Sun reaches its highest point in the sky, and then begins moving lower. At the moment of the June solstice, the Sun is directly overhead some point on the Tropic of Cancer; this is the furthest north that the subsolar point ever reaches. In the Northern Hemisphere the June solstice is called the Summer Solstice (and marks the longest day of the year), while in the Southern Hemisphere it is called the Winter Solstice (and marks the shortest day of the year). The June Solstice is usually on June 21.