This winter starts on Friday, December 22 at 4:27 in the morning, the date and time of the winter solstice. This astronomical event and symbolic moment for many cultures do not always fall on the same day, but usually occurs between December 20 and 23 and marks the beginning of the winter season in the northern hemisphere. The day of the winter solstice is the s the shortest day of the year and the longest night of the year. Let’s look at what happens to the relationship between the Earth and the Sun to understand why this anniversary always falls on these days of the year.
What it is and what happens during the winter solstice
The winter solstice marks the Start official from astronomical winter. As with the equinoxes (spring and autumn), they occur every year in two solstices: once a year in June (which is in the northern hemisphere Midsummer) and once in December (winter solstice in the Northern Hemisphere). But what is happening on this day from a scientific point of view? In addition to rotating daily on its axis (the imaginary line that connects the North Pole to the South Pole), the Earth also rotates around the Sun. The fact that the Earth’s axis is tilted 23°27′ relative to the plane of the Earth’s orbit is the cause of the alternating o season.
What happens during the December solstice is that the sun’s rays reach a minimum inclination relative to the horizon in the northern hemisphere and the greatest slope in the southern hemisphere. Especially at the December solstice, the Sun reaches its zenith along the tropic of Capricorn in the southern hemisphere (light falls perpendicular to the ground and objects do not send further), while above the polar Circle, The sun does not rise above the horizon.
If the earth’s axis were perpendicular to the plane earth’s orbit The sun would be at the zenith everywhere and every day of the year, therefore there would be no solstices, no equinoxes, no seasons, etc. circle of enlightenment (ie the part of the Earth illuminated by the Sun) would always extend from the North Pole to the South Pole.
If we photographed the Sun at the same time every day for a year and in the same place, we would notice that apparent motion of the Sun as it rises and falls over the months, marking the seasonal paths along the sort of tilted figure eight that bears the name analemma. The winter solstice represents the lower end along the axis of the analemma. The summer solstice represents the opposite extreme, and the equinoxes are approximately at the “throttling” point of the analemma.
The solstices don’t last all day: when they fall in 2023
Although the solstice is often thought of as a whole day, it only lasts one day moment: the winter solstice will occur in 2023 on December 22 at 4:27 am (Italian time). The date of the winter solstice is not always the same but can fall within a window of time that changes from December 20 to 23 due to the imperfect match between the solar year and the calendar year.
L’anno solar (i.e., the time it takes the Sun to complete its apparent circular motion across the sky during Earth’s orbit) takes several hours longer than the calendar year OF 365 days and on which our calendar is based: this is why the winter and summer solstices “slip” by approximately 5 hours and 48 minutes from year to year. This delay accumulates but is then partially canceled out by leap years, which introduces an extra day every 4 years.
Because it is the shortest day and longest night of the year
It’s called the shortest day of the year (or rather, the shortest day) for a reason: the winter solstice is the day with fewer hours of light northern hemisphere. This definition is based on the fact that the Sun travels the shortest path across the sky: we will therefore have less daylight and a longer night. From this point, the hours of light will tend to increase until the summer solstice, when they will begin to decrease again.
Contrary to what we sometimes hear, the shortest day (or longest night) is not the day Saint Lucia December 13th, but that is always – by definition – the day of the winter solstice.
Meaning and origin
This fact was already known in ancient times Latin term solstice which roughly means “stopping the Sun”. As is clear from observing the analemma, during the solstices the Sun changes its position in the sky only slightly, so much so that looks still.
Depending on the time of year we are in, this path is different for us observers: in summer the Sun is at noon there will be high in the sky, more in winter Bass, reaching a maximum peak during the summer solstice and a minimum during the winter solstice. Not only that: if we look at our own shadow at noon, on the day of the winter solstice, it reaches its maximum length, while on the summer solstice, it reaches its minimum length.
