kausivaihdelun

Kausivaihdelun, also known as the equinox, is an astronomical event that occurs twice a year, around March 20-21 and September 22-23. The term "kausivaihdelun" is derived from the Finnish words "kausi," meaning season, and "vaihdelun," meaning change. During the equinoxes, the Sun is positioned directly above the Earth's equator, resulting in nearly equal day and night lengths worldwide.

The vernal equinox, which marks the beginning of spring in the Northern Hemisphere and autumn in the Southern Hemisphere, occurs around March 20-21. Conversely, the autumnal equinox, which signals the start of autumn in the Northern Hemisphere and spring in the Southern Hemisphere, takes place around September 22-23. Despite the name, the equinoxes are not the only days with equal day and night lengths. Due to atmospheric refraction and the definition of sunrise and sunset, the actual day and night lengths vary slightly.

Kausivaihdelun is celebrated in various cultures around the world. In ancient Egypt, the equinoxes were associated with the worship of the goddess Isis and the fertility of the Nile. In many cultures, the equinoxes are seen as a time of balance and transition, symbolizing the change from one season to another. In modern times, the equinoxes are often celebrated with festivals, such as the March Equinox Festival in Finland, which features music, dance, and other cultural events.