An equinox is an astronomical event that occurs due to the Earth's tilt on its axis. For half the year, the northern hemisphere gets more daylight while for the other half the southern hemisphere has "longer" days.
What happens during the spring equinox?
The March equinox marks the moment the Sun crosses the celestial equator - the imaginary line in the sky above the Earth's equator - from south to north. This happens on March 19, 20, or 21 every year.
Watch the video below to undersand better.https://youtu.be/kaG6PTVrFP4