Vernal Equinox and Equilux
Written by Anne Newman 19th and 20th March 2019. Updated 2021.
This year's Vernal Equinox falls on 09.37 March 20, 2021. The Vernal Equinox marks the turning point when daylight begins to win out over darkness. This is the moment in the Northern Hemisphere when the Sun crosses the equator and the days and nights are equal in hours. The direct rays of the Sun are shining down on the equator producing the effect of equal day and night.
Vernal means “new”
and “fresh,” and equinox comes from the Latin aequus (equal) and
The Vernal Equinox marks the turning point when daylight begins to win out over darkness. From now until the summer solstice on June 21, the days will gradually get longer because the sun will be higher in the sky, giving more hours of daylight.
More hours of sun means more warming by the sun, so the days will also get warmer. Also the sun's rays will be striking the Northern Hemisphere from a more acute angle, so that the same amount of solar radiation is concentrated in a smaller area, amplifying the heating factor.
If you are standing on the equator at the exact time of the equinox, and the weather conditions are just right, you might find that you cast no shadow. This is because the centre of the sun will be directly overhead.
If you are standing at the North Pole on the spring equinox you will see the sun start to peep over the horizon, signalling the end of six months of darkness and marking the start of six months of daylight. The opposite is true when standing at the South Pole on the spring equinox.
Although popularly described as "the first day of spring" in the Northern Hemisphere, the annual event is actually much more important than that. More than any other event, it marks the beginning of the astronomical year.
Stories have grown up around the equinox. It’s said you can balance an egg vertically on a flat surface, not on other days of the year. The theory goes that at this time of year the moon and earth are in exactly the right alignment, the celestial bodies generating the perfect balance of forces needed to make it possible. The truth is that the amount of sunlight we get during the day has no power over the gravitational pull of the Earth or our abilities to balance things upon it. If you have the patience and a steady hand then you can balance an egg on it's end any day of the year.
There are many sites around the world with an alignment to the Vermal Equinox.
Here are a few. Maybe
you know of others near you?
- Grianan Aileach, Donegal.
- Chichenm Itza in Mexico. The 79-foot pyramid was built by the Mayans about 1000 years ago, outlining the body of Kukukan, a feathered snake god. A serpent-head statue is located at the bottom of the pyramid, and as the sun sets on the day of the equinox, the sunlight and shadow outlines the body of Kukulkan joining with the head.
- Cahokia mounds - Cahokia’s Monks Mound and woodhenge ceremonial area have alignment to the spring equinox. Information on Sunrise observance
- Fajada Butte, Chaco Canyon - Near the top of the Butte are two petroglyph spirals with three large rock slabs positioned near them. The rocks were discovered to direct sunlight onto the spirals, depicting the sun's movement through the year. At spring equinox a display of light is directed on to the smaller snake-like spiral. The dagger is seen on the right of the main spiral.
- AngarWat Cambodia. On the spring equinox, researchers wrote,
“an observer standing at the southern edge of the first projection on the causeway (just in front of the western entrance gate) can see the sun rise directly over the top of the central tower of Angkor Wat.”
- Malta at the prehistoric Mnajdra Site. The spring equinox sunrise bisects the entrance to the Lower Temple, shining light through the main passageway and into a small shrine within the complex.
- Sweden at the megalithic ‘stone ship’ Ales Stenar site.
The word equinox is often understood to mean "equal day and night", this is not strictly true. In fact, the word equinox translates to “equal night.” The equinox is a precise moment in time which is common to all observers on Earth.
Equilux: equal day & night—12 hours of daylight and 12 hours of nightime.
The actual date that will have 12 hours of day and 12 hours of night is known as the equilux (meaning “equal light”) and generally occurs on a different date than the equinox.
For most locations on earth, there are two distinct identifiable days per year when the length of day and night are closest to being equal; the days where sunrise and sunset are closest to being exactly 12 hours apart.
Those days are referred to as the "equiluxes" to distinguish them from the equinoxes.
Because sunset and sunrise times vary with an observer's geographic location (longitude and latitude), the equilux likewise depends on location and does not exist for locations close to the Equator.
check out your location here: Time and Date.com
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Anne is sharing a series of events throughout the year - you can find them listed by clicking to the link Other Notable Dates and Festivals.