Winter Solstice

sun ray tilt

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?

Earth's axis

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 more tilted and the sun's rays arrive almost vertically. This results in less sun, making it the shortest day of the year.

Society generally has a poor view of winter and summer based on the distance from the earth to the sun. Summers are known to be hotter because the earth is closer to the sun, and winters are colder because we are further away. The path of the Earth's orbit around the sun, known as translation, is elliptical. At the spring and winter equinoxes, the Earth and the sun are the same distance apart and at the same tilt. However, contrary to popular belief, the Earth is closer to the Sun in winter and farther away in summer. So how can we be colder in winter?

In addition to the Earth's position relative to the Sun, what affects Earth's temperature is the angle at which the sun's rays strike the Earth's surface. In winter, at the solstice, the Earth is closer to the sun, but its inclination is greater in the northern hemisphere. So when the light hits the Earth's surface too obliquely, the days are shorter and dimmer, so they don't heat up the air as much and it's cooler. In the southern hemisphere, the opposite occurs. These rays hit the earth's surface more vertically and directly, so for them summer starts on December 21. This situation of the earth with respect to the sun is called perihelion.

On the other hand, during the summer, the Earth is farthest from the sun throughout its orbit. However, the tilt of the northern hemisphere causes the sun's rays to strike the northern hemisphere more vertically, making it warmer and longer. This situation of the earth with respect to the sun is called aphelion.

winter solstice and culture

what is the winter solstice

Throughout history, humans have celebrated the winter solstice. For some cultures, the beginning of the year is December 21, coinciding with the beginning of winter. Some Indo-European tribes also have festivals and ceremonies to celebrate the day. The Romans celebrated Saturnalia in honor of the god of the same name, and in the following days they paid tribute to Mithras in honor of the god of light, inherited from the Persians.

For an ancient tradition, the winter solstice represents the victory of light over darkness. Interestingly, this happens when there are fewer daylight hours in winter. However, this is so because from the winter solstice, the nights will be shorter and shorter, and thus, the day will prevail over the night.

The winter solstice also gave rise to many pagan festivals and ceremonies. It is celebrated at Stonehenge on December 21, when the winter solstice sun aligns with the most important rock in the monument. Today in Guatemala the winter solstice is still celebrated with the "dance of the flyers". This dance consists of several people turning around and dancing around a stake.

Goseck's Circle

This circle is located in Saxony-Anhalt, Germany. It consists of a series of concentric rings nailed to the ground. Archaeologists and historians estimate that It is around 7.000 years old and was the scene of religious ceremonies and sacrifices. When they found it, they noticed that the outer ring had two gates aligned with the winter solstice. That is why this suggests that it was built as a tribute to this date of the year.

Stonehenge in England

As we mentioned earlier, the winter solstice is also celebrated at Stonehenge due to the alignment of the sun's rays with the central altar and the sacrificial stone. With a history of about 5.000 years, this monument is almost world famous and it has been an important scene of sacrifices and astronomical observations for hundreds of years.

Newgrange, Ireland

A 5000-year-old tomb in the northeast of Ireland is overgrown with grass and filled with tunnels and canals. Only at the winter solstice does the sun enter all the main chambers, which according to some experts suggests that the structure was built to commemorate the day.

Tulum, Mexico

Located in the Yucatan Peninsula on the east coast of Mexico, Tulum is an ancient walled city that belonged to the Mayans. One of the buildings built there has a hole in the top that creates a flare effect when the days of the winter and summer solstice align with it. The building remained intact until the Mayan population declined with the arrival of the Spanish.

Why does the date of the winter solstice change every year?

Winter Solstice

The day that winter begins can occur on different dates, but it is always around the same day. The four dates on which it can occur are from December 20 to 23, two inclusive. This is due to the way the calendar we have adjusts to the order of the years. Depending on whether the year is a leap year or not, it depends on the duration of each orbit that the Earth makes around the sun. When the Earth revolves precisely around the sun, it is called a tropical year.

Throughout our 20st century, winter will begin on December 22-XNUMX.

winter solstice and climate change

Natural variations in Earth's orbit, including those associated with precession, redistribute incoming solar radiation on Earth's surface over long periods of time.

The precession or wobble of the earth is the movement of a spinning top that rotates like the axis of the earth. The axis describes an imaginary circumference of space, following a rotation every 22.000 years. How does this relate to global warming and climate change?

Over the past few million years, these subtle shifts in the Earth's axis have caused large drops and increases in the concentration of methane and carbon dioxide in the atmosphere. Greenhouse gas concentrations are known to respond primarily to changes in the northern hemisphere's summer, the time of year when the North Pole points toward the sun.

High summer temperatures in the Northern Hemisphere peak every 22.000 years, when northern summer coincides with Earth's closest point to the sun and the northern hemisphere receives the most intense solar radiation.

By contrast, summer heat reaches its lowest value after 11.000 years, once the Earth's axis rotates in the opposite direction. Summer solar radiation will be less in the northern hemisphere because the Earth is farther from the sun.

Over the last 250 years, concentrations of methane and carbon dioxide have risen and fallen in response to changes in solar radiation on Earth.

There is a winter solstice every 11.000 years, because the incoming solar radiation in the northern hemisphere is greater, and conversely, when the precession cycle is complete, there is another winter solstice, which is colder and more inclined because the sunlight. Greenhouse gas concentrations are said to increase naturally because we are approaching the time of precession when the Earth receives more solar radiation, but we are well aware that nature will not increase that much, rather it is due to human activity to increase drastically the average global temperature.

I hope that with this information you can learn more about the winter solstice and its characteristics.


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