When is the spring equinox?
The Spring equinox takes place on Sunday 20 March and marks the official beginning of Spring in the Northern Hemisphere.
However due to the Earth’s elliptical orbit of the sun, the date changes slightly every year.
There are two vernal equinoxes each year - in Spring and Autumn.
Why is it called an 'equinox'?
The name “equinox” comes from the Latin, meaning “equal night”, because the the day and nighttime are nearly equal in length.
It takes place when the sun is shining directly on the equator.
The exact moment of the equinox is when the Sun crosses the celestial equator (an imaginary line above the earth’s equator), running north to south. This will happen at 4.30am in 2016.
Spring equinox traditions
Many cultures celebrate festivals and holidays around the equinox, such as Easter in Christianity, Holi in Hinduism and Passover in Judaism.
The Persian new year, known as Nowruz, is also celebrated at this time.
Perhaps one of the most famous traditions around the equinox was held at the Mayan site of Chichen Itza, Mexico.
The Temple of Kulkan, dedicated to a feathered serpent god and known for bloody sacrifices, is built so that on both the Spring and Autumn equinox, the northwest corner of the pyramid casts a series of shadows which look like a snake slithering down its side.
A number of people often gather at Stonehenge in Wiltshire to celebrate the event as well.