Napéjegyenlségek

Napéjegyenlségek, often translated as equinoxes in English, are astronomical events that occur twice a year, around March 20 or 21 and September 22 or 23. During an equinox, the Sun is directly above the Earth's equator, meaning that day and night are of approximately equal length all over the world. This phenomenon is a result of the Earth's axial tilt. The Earth's axis is tilted at an angle of about 23.5 degrees relative to its orbital plane around the Sun. As the Earth orbits the Sun, this tilt remains relatively constant.

The March equinox marks the beginning of spring in the Northern Hemisphere and autumn in the Southern Hemisphere. Conversely, the September equinox signifies the start of autumn in the Northern Hemisphere and spring in the Southern Hemisphere. The word "equinox" itself comes from the Latin words "aequus" meaning equal and "nox" meaning night, reflecting the nearly equal duration of daylight and darkness. While often described as exactly 12 hours, the actual length of day and night can vary slightly due to factors such as atmospheric refraction and the definition of sunrise and sunset. The precise timing of the equinoxes is determined by the Earth's orbital position and is calculated annually.

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