Vernal or Spring Equinox is an astronomical event, which marks the start of spring in the Northern Hemisphere. Spring Equinox is observed every year on March 20th or 21st. This year, Spring equinox will take place on March 20 i.e., Saturday, starting at 5.37 am EST and 3:06 pm IST.

What is Equinox?

An equinox occurs when the Earth’s axis is titled in a way that is neither inclined away from the Sun nor towards it. Equinox word comes from Latin words ‘aequi’ that means equal and ‘nox’, which means ‘night’, which becomes ‘equal night.’ On an Equinox day, the duration of day and night are almost equal.

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Equinoxes occur two times every year, once to mark the start of Spring, another that marks the end of astronomical summer. 

Why does Vernal Equinox mark the start of summer?

On the day of Vernal Equinox, the sun directly shines on the Earth’s equator resulting in equal minutes of daylight and darkness around the globe. 

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According to a website, Space.com, Earth’s orbit keeps changing its orientation relative to the Sun, resulting in Earth’s axis constantly point in a different direction. As per the website, the seasons are defined as “beginning at strict 90-degree intervals,” which happens on Equinox days. 

While Vernal Equinox marks the beginning of spring in the Northern Hemisphere, it marks the start of autumn in the Southern Hemisphere.