Spring has historically started on the day of the vernal equinox, which occurs on the night of 20/21 March.
An equinox is one of two times during the year when the length of day and the length of night are just about equal while the word vernal comes from the Latin word for bloom.
It refers to the fact that this equinox marks the end of winter and the beginning of spring in the northern hemisphere.
Astronomers have defined an equinox as that moment when the sun arrives at one of two intersection points of the ecliptic, the sun’s path across the sky, and the celestial equator, earth’s equator projected onto the sky.
The date is particularly significant for pagans, many of whom carry out rituals, while others indulge in activities such as egg races, egg hunts and egg eating and egg painting. A number of Spring harvest festivals are celebrated at this time while Vernal Equinox Day is a national holiday in Japan, when families visit graves and hold reunions.
The Persian new year, Nowruz, also corresponds with the vernal equinox while many Iranians, Kurds and others will celebrate the 13-day festival.