First Day of Spring 2013: Vernal Equinox begins March 20th

The Vernal Equinox, also known as the March Equinox, begins on Wednesday, March 20th. On the first day of spring, the sun will shine directly on the equator and the length of the day and night are almost exactly the same.

Why is it called equinox?

On the equinox, night and day are nearly exactly the same length – 12 hours – all over the world. This is the reason it's called an "equinox", derived from Latin, meaning "equal night".

The March equinox occurs 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 either on March 19, 20 or 21 every year. On any other day of the year, the Earth's axis tilts a little away from or towards the Sun. But on the two equinoxes, the Earth's axis doesn't tilt neither away from nor towards the Sun.

Cultural Importance of the Vernal Equinox

Modern astronomy aside, people have recognized the vernal equinox for thousands of years. There is no shortage of rituals and traditions surrounding the coming of spring. Many early peoples celebrated for the basic reason that their food supplies would soon be restored. The date is significant in Christianity because Easteralways falls on the first Sunday after the first full moon after the vernal equinox. It is also probably no coincidence that early Egyptians built the Great Sphinx so that it points directly toward the rising Sun on the day of the vernal equinox.

The first day of spring also marks the beginning of Nowruz, the Persian New Year. The celebration lasts 13 days and is rooted in the 3,000-year-old tradition of Zorastrianism.

There is an urban legend that you can balance an egg on its point during the equinox. I dare you to try it.