Dusk, a moment of the day that lasts more than a moment but that often cannot be clearly located. Between sunrise and full day, between full day and sunset... when are we observing the twilight? Maybe we're photographing it to post it on Instagram and we don't even know that's exactly what it is.
With this term we want to identify the interval of morning and evening time, so both before dawn and after sunset, where sunlight is visible, yes, but only because the atmosphere spreads it and not because the sun itself is in front of our eyes.
We can meet in ours "crepuscular" searches three types of this phenomenon: civil, nautical and astronomical. In civilian, whether in the morning or in the evening, it is possible to clearly distinguish the objects around us and usually we can walk around in the street as if it were day without the need for street lamps and supplementary lighting, however, no stars are visible in the sky, with a few bright exceptions.
The nautical twilight it is defined as the time frame in which we can distinguish both the horizon line and the main stars, this means that nautical measuring instruments are able to establish their own geographical location. That astronomical occurs when the sun is below -18 ° from the horizon therefore it no longer illuminates the sky substantially but on Earth we can still, or already, distinguish the stars and objects around us with the naked eye.
Twilight in English
In English we use the term "dusk " which is sometimes translated as sunset, in truth.
Such a magical moment, with an almost surreal light, has inspired many poets over the years, including Eugenio Montale who wrote "Two in the twilight". Let's read the first lines.
“It flows between you and me on the lookout
an underwater glow that deforms
even your face with the profile of the hills.
It lies in an elusive, severed bottom
from you every gesture of yours; enters without a footprint,
and disappears, in the middle it fills
every furrow and closes on your step:
with me you here, in this fallen air
the torpor of the boulders ". (...)
Twilight of the gods
If this name sounds to you, you are perhaps a music lover, because it is the title of the fourth and last of the musical dramas that make up the tetralogy. The Nibelungo ring of Richard Wagner. The story tells a sort of armageddon of the world in Nordic mythology, in Italy the first was on April 18, 1883 at the Teatro La Fenice in Venice.
You cannot make an appointment with the Twilight because the time in which it comes to us depends a lot on our geographical location as well as on the season in which we find ourselves. The duration of twilight is also not fixed at all, it varies according to the place taken into consideration and of the position of the Earth with respect to the Sun.
Usually at high latitudes we witness longer twilights and there is also the midnight sun when twilight is not even there because the sun does not set.
Near the geographic poles, during the dark semester, there are twilights that last several weeks, in general, however, at other latitudes, the shorter ones are seen in the equinoxes, the longest in the solstices, but if we are at the equator the duration of twilight is almost constant.
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