On Tuesday, March 19, the inhabitants of the northern half of the Earth will experience an astronomical event marking the end of winter and the official beginning of spring. This event is known as the Spring Equinox, when the length of day and night is approximately equal everywhere on Earth.
**What is the Equinox?**
As the Earth orbits the Sun, it tilts at about a 23.5-degree angle. On most days of the year, the Earth's axis leans either toward or away from the Sun. This results in uneven distribution of warmth and light from the Sun across the northern and southern hemispheres of the planet. During the equinox, the Earth's axis and its orbit align so that both hemispheres receive an equal amount of sunlight. The term "Equinox" is derived from the Latin words *aequus*, meaning equal, and *nox*, meaning night. Thus, on the day of the equinox, day and night last nearly the same amount of time, although a person may experience a few extra minutes of daylight depending on their location on the planet.
**What is the Difference Between Meteorological and Astronomical Seasons?**
Meteorological seasons are determined by weather patterns and are divided into three-month periods based on annual temperature cycles. According to this calendar, spring begins on March 1, summer on June 1, autumn on September 1, and winter on December 1. Meanwhile, astronomical seasons depend on the Earth's movement around the Sun and the occurrence of the summer and winter solstices and the spring and autumn equinoxes. The spring equinox in the northern hemisphere can occur between March 19 and March 21, depending on the year.
Solstices mark the times of the year when the Earth is tilted at its maximum angle towards or away from the Sun. This means that the two hemispheres receive very different amounts of sunlight, resulting in unequal lengths of day and night. During the summer solstice in the northern hemisphere, the upper half of the Earth tilts toward the Sun, creating the longest day and the shortest night of the year, occurring between June 20 and June 22. Conversely, in the winter solstice, the northern hemisphere tilts away from the Sun, resulting in the shortest day and the longest night of the year, occurring between December 20 and December 23.
