Little is missing fromspring equinoxwhich officially starts the first mild season of the year: the March 20, to be exact at 10.12 Italian timewe will greet winter and welcome spring.
The myths to dispel (and what is true)
At the spring equinox the day and night have exactly the same duration everywhere false
As explained by the National Institute of Geophysics and Volcanology (INAF)
The spring equinox is the position taken by the earth in the intermediate point between the two solstices
In the figure, the sun-e right (with and the position of our planet to the equinox itself) divides the upper ellipse in two equal areas which means two equal timesfor the second law of Kepler, who says that a celestial body moves faster when it is at Perdie (the point closest to the sun) and more slowly to the infelium (the point farthest from the sun).
So is it true that at the spring equinox the day and night have exactly the same duration? No, or rather, not in general. Actually Only those who are on the equator to longitude corresponding to the mezzogiorno meridianat the time of the spring equinox, he can truly experience a length of the day exactly identical to that of the night.
In other words, those who live on the M1, M2, M3 points of the figure below will have different days/nights, because, when they find themselves with their meridian at noon, the earth will have moved a little forward or will still have to reach point E.
For every longitude on the earth that the spring equinox is the day such of such but also at the time of such corresponding to the moment when “somewhere” is noon
At the spring equinox the day and night have exactly the same duration at least on the mezzogiorno meridian not exactly true
In reality there is also a clarification for those who live on the notorious mezzogiorno meridian. Inf explains on this:
If we assume that the duration of the day is the time between the dawn and the sunset (analogous reasoning is true for the night) it must be considered that this duration is the sum of the alba-mezzogiorno southern-voucher. These two times are not the same because at dawn the earth is located a little before the point and at sunset a little after the same point and, therefore not exactly to the equinox
In short, to be just super precise, No pointat the spring equinox, really lives the same duration in the day and night.
Among other things, as it also reports Star Walkthe dawn and sunset are described as the moment when the upper part of the sun touches the horizon, and therefore, to really sunset, the sun must be completely descended under the horizonoperation that may also take several minutes. Also, at sunset the refraction of sunlight Determined by the Earth’s atmosphere makes us see the sunlight for several minutes despite the fact that it is already under the horizon. Also for all this, during the equinoxes, the day is slightly longer than the night.
There is a particular day in which 12 hours of light and 12 hours of real darkness occur but …
Yes, in reality there is a day in which 12 hours of light and 12 of darkness really occur (even if there is always the waste of a few dozen seconds), but it is not at the equinox (neither of spring, nor autumn): it’s called Equiluceand the spring equinox falls a few days earlier and a few days after the autumn equinox, but also in this case the exact day depends on the latitude.
The spring 2025 equinox (with the shooting stars)
The March 20, to be exact at 10.12 Italian timewe will greet winter and welcome spring. And, if we wait for the night, we can also admire some falling star. In fact, just a few hours later, in the night between 21 and 22, the Main peak of the Virginidswe explain it here: Welcome spring with the shooting stars, we prepare other desires!
Happy spring to all!
