The Earth orbits around our star, the Sun. Along its path, it travels different distances from it. The arrival of Winter Solstice coincides with the shortest days and longest nights in the northern hemisphere, and vice versa in the southern hemisphere. This day is usually December 21. The winter solstice is a key event that marks changes in natural and astronomical cycles. Beginning with the winter solstice, the nights in the Northern Hemisphere begin to gradually shorten until the summer solstice in June.
In this article we are going to tell you everything you need to know about the winter solstice, its characteristics and importance.
What happens at the winter solstice?
During the winter solstice, the Earth reaches a point in its orbit where the sun's rays strike the surface at the steepest angle. This happens because the Earth is tilted about 23,5 degrees from the perpendicular of its orbit. As a result, at this time of year, the northern hemisphere is oriented so that it receives less sunlight, causing it to be the shortest day of the year in terms of hours of sunlight.
Many people tend to think that winter is colder because the Earth is farther from the Sun, but this is incorrect. In fact, the Earth is at its closest point to the Sun (perihelion) at the beginning of January, but the northern hemisphere still receives less light due to the angle at which the Sun's rays hit at this time of year.
This angle makes the sun's rays less intense and, therefore, less warming to the surface. As we move away from the equator towards the poles, this inclination of the Earth causes the days to be shorter and the nights to be longer and colder, which is characteristic of winter. In the southern hemisphere, the opposite occurs; here, the winter solstice marks the beginning of summer, with December 21 being the longest day of the year and with the highest solar radiation.
An interesting astronomical phenomenon related to the solstices is that, in places close to the polar circles, such as Alaska or Norway, there are days without sunlight, known as the polar night, which can last up to six months near the poles. Meanwhile, in the south the opposite occurs, with days of continuous sunlight.
winter solstice and culture
Throughout history, humans have celebrated the winter solstice in different ways. In many ancient civilizations, this event marked a moment of renewal and hope, as it symbolized the end of the darkest time of the year and the gradual return of light.
The solstice was considered a sacred time in many cultures. In the Celtic world, for example, Yule was celebrated, a festival that celebrated the rebirth of the sun. The Celts lit fires and made offerings to the rebirth of the star.
In Rome, Saturnalia was celebrated, a festival in honor of the god Saturn, which symbolized the opportunity to leave the past behind and start a new life.
Goseck's Circle
Located in Saxony-Anhalt, Germany, the Goseck's Circle It is a series of concentric stone rings dating back some 7.000 years. Although its exact purpose is not known for certain, many believe it was used as a solar observatory, as the outer doors are aligned with the Sun during the winter solstice. This alignment suggests that the ancient inhabitants of the area understood the astronomical significance of the solstice and used it to mark the passage of time.
Stonehenge in England
Perhaps more famous is Stonehenge In England, a 5.000-year-old stone monument is also aligned with the winter solstice. During the sunrise on this day, the sun's rays align precisely with the stones of the monument, creating a stunning effect. This event attracts thousands of tourists and devotees every year, who gather to witness the sunrise and celebrate the beginning of the new solar cycle.
Newgrange, Ireland
Similar to Stonehenge, newgrange In Ireland, there is a 5.000-year-old tomb that is aligned with the sunrise of the winter solstice. During this day, the sun's rays penetrate directly into the heart of the structure, illuminating its inner chambers. Many experts believe that this alignment was not accidental, but was deliberately designed to highlight the symbolic importance of the solstice.
Tulum, Mexico
In the ancient Mayan city of TulumLocated on the Yucatan Peninsula, one of the temples is aligned with the winter solstice. At sunrise on this day, the sun's rays pass through a small window at the top of the temple, creating a light show that many believe had a ritual and religious purpose for the Mayans.
Why does the date of the winter solstice change every year?
The calendar that we humans use is not perfectly aligned with astronomical cycles. tropical year, which is the time it takes the Earth to complete one full revolution around the Sun, lasts approximately 365,24 days. To make up for that extra fraction of a day, we introduce leap years every four years, allowing us to keep our calendar in sync with the seasons. However, because of these adjustments, the exact date of the winter solstice can vary between December 20 and December 23.
winter solstice and climate change
One common question is how climate change might affect the solstices and the seasons in general. Variations in the Earth's orbit, such as precession or the wobbling of the Earth's axis, occur over thousands of years and affect the angle and intensity of sunlight that the Earth receives in different seasons.
Throughout geological history, these variations have caused fluctuations in the Earth's climate, including periods of cooling and warming. However, the global warming we are currently experiencing is a consequence of human activities, such as greenhouse gas emissions. Although the seasons will continue to occur as they have for millions of years, the effects of climate change may make winters less cold in some areas and more severe in others.
Over time, the seasons have gradually shifted due to precession, a wobble in the Earth's axis that occurs on a cycle of about 26.000 years. This phenomenon may seem subtle in the short term, but over millennia it has caused significant variations in climates and seasons.
How does the winter solstice affect nature?
The winter solstice not only affects humans and our cultures, but also influences nature.
- Hibernation: Many animals, such as bears and some rodents, take advantage of this period to hibernate, conserving energy until warmer days arrive with greater food availability.
- Revitalization of vegetation: Perennial plants may appear dormant during the winter, but at the cellular level, they continue to perform vital functions, preparing for spring.
In short, the winter solstice, in both the Northern and Southern Hemispheres, is an astronomical phenomenon that not only marks the change of season, but also a time of rebirth and renewal in many cultures and ecosystems around the world.