Day and night are equal the northern hemisphere officially witnesses the beginning of spring

On Tuesday, March 19, residents of the Northern Hemisphere will witness an astronomical event that announces the end of winter and the official beginning of spring.

This event is known as the vernal equinox, when the length of day and night are approximately equal everywhere on Earth.

When the Earth revolves around the Sun, it is tilted at about 23.5 degrees. On most days of the year, the Earth's axis tilts either toward or away from the sun. This means that the Sun's warmth and light fall unevenly on the northern and southern halves of the planet.

During the equinox, the Earth's axis and orbit align so that both hemispheres receive an equal amount of sunlight.

The word Equinox comes from the Latin words aequus, which means equality, and nox, which means night. This is because on the day of the equinox, day and night last approximately the same amount of time, although one may get a few extra minutes, depending on where they are on the planet.

What is the difference between meteorological and astronomical seasons?

Meteorological seasons are determined by the weather. The year is divided into three-month seasons 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.

While the astronomical seasons depend on how the Earth moves around the sun, and on the occurrence of the summer and winter solstices, and the spring and autumn equinoxes.

The vernal equinox in the Northern Hemisphere can occur between March 19 and 21, depending on the year. 

The solstices represent the times during the year when the Earth is at its greatest tilt toward or away from the sun. This means that the two hemispheres get very different amounts of sunlight, and day and night are not at all equal.

During the summer solstice in the Northern Hemisphere, the upper half of the Earth tilts toward the sun, creating the longest day and shortest night of the year. This coup occurs between June 20 and 22.

At the winter solstice, the northern hemisphere is tilted away from the sun, resulting in the shortest day and longest night of the year. The winter solstice occurs from December 20 to 23.