Many celebrate the beginning of spring, which is also the world day of poetry and much more, but you are not always aware of what is happening between the sky and the earth, between the Earth and the Sun, while preparing for the summer. The days get longer, we realize that at dinner time there is still light and in the morning you no longer get up wrapped in darkness or in the light of dawn. However, there is a turning point in this lengthening of the bright part of the day, it is called spring equinox.
Spring equinox: what it is
From the Latin aequinoctium, derived in turn from "Aequa-nox" , equinox means "equal night" precisely because it refers to that day of the year in which the duration of the night period is perfectly equal to that of the day. Seen from another, more astronomical point of view, we can say that this day coincides with the moment of the earth's revolution around the Sun in which the latter is located at the zenith of the equator.
Intuitively, there cannot be just one equinox in a year, in fact, in addition to that of spring there is also the autumn one that falls in the period in which we have the hours of light that fall and those of darkness that increase. Besides the fact that the day and night periods are the same, something else happens during the spring equinox: the sun's rays arrive perpendicular to the rotation axis of the Earth.
The equinoxes fall at approx six months apart from each other, that of spring in March, that of autumn in September, the solstices are also six months apart, that of winter, in December, and that of summer, in June. The seasons by convention start in these very comfortable days to keep pace with nature, the sky and the earth.
We must be careful about the hemisphere in which we are, to define the equinoxes, however, because in the northern one the spring equinox marks the end of winter and the beginning of spring, while that of September ends summer and introduces autumn but in the southern hemisphere the opposite happens and that of March is the day that marks the beginning of autumn.
Spring equinox: what happens
Everyone knows that the axis of earth's rotation it is not perpendicular to the orbital plane of revolution around the Sun, in fact it is inclined on average by 23 ° 27 ′. Why is it so important? Because this inclination means that the light of the Sun never affects, at any moment, at the same angle. The rays come to us with an inclination that varies constantly and only at the equinoxes do they arrive perpendicular. This is because only in these two days of the year the earth's rotation axis is perpendicular to the direction of the sun's rays. Also for this reason the daytime duration is the same as the nighttime one.
If we take the spring equinox, reasoning like those who live in the northern hemisphere, we find it also referred to as the vernal point, Aries point or gamma point from the Greek lowercase letter γ, whose shape resembles the head of a ram. The autumn equinox it falls in September and is also called the Libra point or the omega point Ω, again because of the shape of the letter.
Spring equinox: when it occurs
The March equinox, that of the boreal spring, often falls on the 20th and, starting from 2044, occasionally also on the 19th of March. Why this advance? Due to the organization of the leap days in the Gregorian calendar which led to the maintenance of the four-year alternation for the year 2000, and therefore caused a progressive shift of one day of all celestial events. This applies to all the years that separate us from the next realignment, expected in the year 2100.
It's not over. The Earth's revolution motion around the Sun it is slightly slower near the terrestrial aphelion, in July, due to Kepler's second law, therefore the September equinox, autumnal, can be slightly later than that of March, Normally it falls around 23 September.
Spring equinox 2020
The spring equinox in 2020 it will take place tomorrow 20 March 2020 at 4.49 am.
It occurred on March 20 also in 2019 and 2018 even if conventionally it is said that the seasons always start on March 21, June, September and December. The convention is a convention but from the astronomical point of view it must be taken into account that the dates are different for equinoxes and solstices, the exact ones do not follow conventions but depend on the Earth revolution. It has been calculated that up to 2102 the vernal equinox will not be March 21, but 20 or, sometimes, 19.
Spring equinox: aphorisms
The flowers of spring are the dreams of winter told, in the morning, at the angels' table. (Khalil Gibran)
If you have the courage to look at the light, imitate spring and move forward towards it. (Markku Envall)
A man can kill a flower, two flowers, three ... But he can't stop spring. (Mahatma Gandhi)
I would like to do with you what spring does with cherry trees. (Pablo Neruda)
Tell me about God, I said to the almond tree. And the almond blossomed. (Nikos Kazantzais)
It is that you are behind things, Spring, who begins to write in the humidity, with the fingers of a playful child, the delirious alphabet of the time that returns.(Pablo Neruda)
I feel like a field sown in the heart of winter, and I know that spring is coming. My streams will start flowing and the little life that sleeps in me will rise to the surface at the first call. (Kahlil Gibran)
Winter has not yet gone, and the apple tree appears suddenly transformed into a cascade of fragrant stars. (Pablo Neruda)
If you want themed poetry instead, you can find them in the article "Poems about flowers in spring“