A solstice occurs twice a year when the Sun reaches its highest or lowest point in the sky at noon, resulting in the longest and shortest days of the year. The two solstices are known as the summer solstice and the winter solstice. The summer solstice, occurring around June 21, has the most daylight, while the winter solstice, around December 21, has the least. These events are caused by the tilt of the Earth's axis as it orbits the Sun. During the summer solstice, the Northern Hemisphere is tilted toward the Sun, while during the winter solstice, it is tilted away. This axial tilt is responsible for the changing seasons.