What is the spring equinox?

The first supermoon of the spring equinox in 19 years will appear in our skies in a few hours’ time, an event that won’t take place again until 2030.

A supermoon is when the Moon is at its closest possible point to Earth. Because the Moon’s orbit is egg-shaped and its size varies each lunar cycle, a full moon at this position is a spectacular sight.

National Geographic reports that tonight’s supermoon will be especially close to Earth. This will cause the lunar disk to appear 14% larger and 12% brighter than usual.

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What is the spring equinox?

It’s the instant of time when the sun crosses over the Earth’s equator. Astronomically the spring equinox marks one of the four major turning points in the Earth’s cycle. As the Earth is tilted on an axis, for most of the year either the north or south hemisphere have longer days, due to one or other being closer to the Sun.

This is not the case in the September and March equinoxes when both poles of the planet are equidistant from the Sun. Hence the March equinox marks the start of spring in the Northern Hemisphere and autumn in the Southern.

How did it get its name?

From a Latin word meaning “equal light”. The term refers to the phenomenon of the Sun passing over the celestial equator, resulting in an equal length day and night for both north and south.

Where does our fascination with it come from?

Originally it was all about survival. In ancient cultures understanding the sun’s changing path was an essential part of human survival. It’s therefore not surprising that cultures around the world often built structures designed to capture the light of the equinoxes and solstices, and used them to mark their calendars.

The spring equinox has long been celebrated as a time of rebirth and abundance. For the Mayans, for example, this meant a sacrificial ritual to the snake deity Kukulkan at the main pyramid in Chichen Itza in Mexico’s Yucatan Peninsula.

Meanwhile, Stonehenge, Ireland’s Grianan of Aileach, Angkor Wat in Cambodia, and Mnajdra in Malta are all designed to be hit by the Sun during the equinox.

How is it celebrated today?

In a number of different ways. In Iran, for example, the equinox takes place during the festival of No Ruz which means “new day” and celebrates a time of hope and rebirth. The Iranian new year also begins on the day of the equinox.

The ancient Hindu festival Holi, which is mainly celebrated in India and Nepal, is an annual event that takes place as the equinox approaches. Also known as the festival of colours, it represents the victory of good over evil. Festival-goers celebrate by throwing brightly coloured powders at one another.

Back in the UK, hundreds of people travel to Stonehenge every year dressed as pagans in order to walk the grounds and watch the sunrise through the rock structures.

When can you see the supermoon?

After sunset tonight, just as the moon rises.