pööripäev

Pööripäev, meaning solstice in Estonian, refers to two specific days in the year when the Sun reaches its highest or lowest point in the sky. This celestial event marks the longest day of the year, the summer solstice, and the shortest day of the year, the winter solstice. The term "pööripäev" literally translates to "turning day" because after the solstice, the Sun's apparent path in the sky begins to change direction, moving from its extreme towards the opposite extreme.

The summer solstice, usually occurring around June 20th or 21st in the Northern Hemisphere, is when the North Pole is tilted most directly towards the Sun. This results in the longest period of daylight and the shortest night of the year. Conversely, the winter solstice, typically on December 21st or 22nd, occurs when the North Pole is tilted furthest away from the Sun, leading to the shortest day and the longest night. The Earth's axial tilt of approximately 23.5 degrees is the cause of these seasonal variations and the occurrence of solstices.

Throughout history, pööripäev has been observed and celebrated by various cultures with festivals and rituals, often tied to agricultural cycles and astronomical observations. These events hold significant cultural and historical importance, symbolizing transitions and the changing of seasons. The precise date of the solstice can vary slightly each year due to the Earth's orbit not being a perfect circle and the complexities of the Gregorian calendar.