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March Equinox: March 20, 2014, 16:57 UTC

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".

Illustration image

The Earth's position during the equinox (ill. not to scale).

March Equinox in Washington DC, District of Columbia, U.S.A. was on
Thursday, March 20, 2014 at 12:57 PM EDT (Change city)

March Equinox in Universal Coordinated Time was on
Thursday, March 20, 2014 at 16:57 UTC

What happens during an equinox?

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.

The Earth's axis is always tilted at an angle of about 23.5° in relation to the ecliptic, the imaginary plane created by the Earth's path around the Sun. However, the tilt's orientation changes throughout the 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 tilts neither away from nor towards the Sun and is perpendicular to the Sun's rays, like the illustration shows.

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". However, even if this is widely accepted, it isn't entirely true. In reality equinoxes don't have exactly 12 hours of daylight

                                           June Solstice | December solstice | September equinox

Illustration image

Spring Equinox at Chichen Itza, Mexico, with the sunlight forming the snake on the staircase.

©iStockphoto.com/CostinT

Celebrating new beginnings

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.

Holidays around the September equinox.

Cultural importance

Equinoxes – along with solstices – have been celebrated in cultures all over the world for as 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.

The snake of sunlight

The main pyramid – also known as El Castillo – has four staircases running from the top to the bottom of the pyramid's faces, notorious for the bloody human sacrifices that used to take place here.

The staircases are built at a carefully calculated angle which makes it look like an enormous snake of sunlight slithers down the stairs on the day of the equinox.

Illustration image
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Watch the sun move across the sky.

Knowledge of the equinoxes and solstices is also crucial in developing dependable calendars, another thing the Mayans and their predecessors clearly had gotten the hang of.

The Mayan calendar was very precise in this respect, but today the Mayan calendar is most famous for ending exactly at 11:11 UTC on the 2012 December Solstice .

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