It's the First Day of Spring!

Most of us think of Spring in terms of flowers, grass needing mowing, birds chirping in the early morning, and warmer temperature, there’s more to it than that. It’s also about the equinox.

The word equinox is derived from the Latin words meaning “equal night.” There are two equinoxes every year – in March and September– when the sun shines directly on the equator and the length of day and night is nearly equal. Seasons are opposite on either side of the equator, so the equinox in March is also known as the "spring equinox" in the northern hemisphere. However, in the southern hemisphere, it's known as the "autumnal (fall) equinox". The Southern Hemisphere: (Australia, New Zealand, South America, Southern Africa). The Northern Hemisphere: (USA, Central America, Canada, Europe, Asia, northern Africa).

The spring and fall equinoxes are the only dates with equal daylight and dark as the Sun crosses the celestial equator—12 hours – all over the world. At the equinoxes, the tilt of Earth relative to the Sun is zero, which means that Earth’s axis neither points toward nor away from the Sun.

But, though accepted, it isn't entirely true. Equinoxes don't have exactly 12 hours of daylight though. On these two days, the geometric center of the sun is above the horizon for 12 hours, and one might think this would indicate that the length of the daylight would be the same. Sunrise is defined as the instant when the upper edge of the sun's disk becomes visible above the horizon – not when the center of the sun is visible. In the same sense, sunset refers to the moment the upper edge disappears below the horizon. At both instances, the center of the sun is below the horizon, and therefore the equinox day lasts a little longer than 12 hours. The Sun is visible longer than 12 hours on an equinox because the Earth's atmosphere refracts sunlight. Refraction causes the Sun’s upper edge to be visible from Earth several minutes before the edge reaches the horizon. In the evening, we can see the sun for several minutes after it has dipped under the horizon. This causes every day on Earth, and not just the equinoxes, to appear at least 6 minutes longer than it does.

The March equinox occurs the moment the sun crosses the celestial equator. It’s an 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 neither tilts away from nor towards the sun.

Equinoxes – along with solstices – have been celebrated in cultures all over the world for long as we have written history. One of the most famous ancient Spring equinox celebrations was the Mayan sacrificial ritual by the main pyramid in Chichen Itza, Mexico.

In the northern hemisphere, the March equinox marks the start of spring and has long been celebrated as a time of rebirth. Many cultures and religions celebrate or observe holidays and festivals around the March equinox, like the Easter and Passover. There is also some weird traditions connected to the Spring Equinox.

Such as:

An ancient Chinese belief says that you can stand an egg on its end on the first day of spring.

The theory goes that, due to the sun's equidistant position between the poles of the earth at the time of the equinox, special gravitational forces apply.

This is, of course, nonsense. But it does still make for a fun party game - and you can save your eggs to paint on Easter Day.

Holi is an ancient Hindu festival celebrating the victory of good over evil. It takes place each year around the time of the vernal equinox.

Known as the "festival of colors", it is celebrated by tossing vibrant coloured powders onto each other and dancing in the streets.

The symbolic plant of the equinox in Druidry is the trefoil or shamrock, which is also customarily worn on St. Patrick's Day.

The three leaves shaped like hearts were associated with the Triple Goddess of Celtic mythology, otherwise known as the "Three Morgans"

The shamrock is thought to be symbolic of the regenerative powers of nature.

The spring equinox is symbolic of rebirth, renewal, and growth, and in ancient Italy, it was traditional for women to plant seeds in the gardens of Adonis on this day.

The custom persists in Sicily, where women plant seeds of grains - lentils, fennel, lettuce or flowers - in baskets and pots.

When they sprout, the stalks are tied with red ribbons and the flowers are placed on graves on Good Friday, symbolising the triumph of life over death.

Many of the world's ancient monuments were built as astrological calendars, to map the movement of the Sun over the course of the year.

The equinox is therefore a great time to visit these monuments, as they are often aligned to make the most of the Sun's unique position in the sky.

At Stonehenge in Wiltshire, the sun can be seen rising precisely between two stones, while at Chichén Itzá in Mexico, the rising sun transforms one edge of the giant pyramid into a blazing serpent, representing the Mayan god Kukulcan.

What does spring mean to you. And how do you celebrate it?