Winter solstice simplified

December 16, 2017

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Illustration by Muhammad Faizan
Illustration by Muhammad Faizan

The sun gets a bit put off by Earthlings during winter, it doesn’t shine in all its glory and seems to move further away in the sky than its usual position during the rest of the year. The days are short and cold, and the nights are longer and colder. Soon we are going to see the longest night of the year and the shortest day when winter solstice will take place on December 21.

Interestingly, as you all know, winter occurs in two phases on Earth — mid-year in the Southern Hemisphere, and late to early in the calendar in the Northern Hemisphere. So, when in December we have the longest night and the shortest day of the year, those living south of the Equator experience the longest day and shortest night of the year. For them, it is the summer solstice.

The seasons go the opposite way in countries north and south of the equator. But while opposite things are happening in the two hemispheres, they are happening at the same time, as the December solstice occurs at a specific time, not just day, for everyone, everywhere on Earth.

time, not just day, for everyone, everywhere on Earth.

This year it is at 9.28pm, Pakistan time. At this point, the sun will shine directly over the Tropic of Capricorn, the farthest south the sun will reach or the most the Northern Hemisphere will tilt away from the sun and so receiving the least amount of sunlight on that day.

Solstice simplified

The term “solstice” is derived from the Latin words sol (sun) and sistere (to stand still), so it means “sun standing still”. This is because the sun appears to stand still, and its relative position in the sky at noon does not appear to change much during the solstice and the days before and after it.

Seemingly standing still at the Tropic of Capricorn, it is when the North Pole is tilted farthest away from the Sun, resulting in the fewest hours of sunlight of the year. The sun then reverses its direction and its most southerly declination of -23.5 degrees.

After the solstice, the days in Northern Hemisphere will start to grow longer and this finally leads to the longest day of the year (only north of the Equator) on June 21.

Astronomical and meteorological winter

While we do know that more than one scale and standard of measuring different things are used around the world, most of us do not know that winter is of two types. Seriously?

Well, winter as we generally tend to relate to, begins on December 1, and ends on February 28, or on February 29 during leap years. These are the three calendar months when the average temperature is the lowest during the year, and this is the meteorological winter.

Astronomical winter begins with the winter solstice, generally on December 21st, and ends on March 19th. This is based on the Earth’s orbit around the sun.

What causes the solstices and the seasons?

The Earth’s tilt! Let’s see how ….

The Earth and all the other planets are moving in two different directions in the Solar System. First is the orbit of the Earth round the Sun in one year, then the Earth also spins around on its axis each day to bring about day and night. The axis of that spin, though, is not exactly perpendicular to the plane of its orbit. Instead, it’s tilted by roughly 23 degrees. And if you pay attention to a physical globe in schools and other places, you will see that this is how it is tilted on it too!

When Earth orbits the Sun, the North Pole is pointed toward the North Star, Polaris. And in its orbit around the sun, part of the year the Northern Hemisphere is tilted toward the Sun, and away from the Sun at other times.

When the tilt of the Earth is towards the Sun, it appears higher in the sky and so heats the ground more directly and leading to longer days. This brings summer in the Northern Hemisphere. At this time the South Pole is tilted away so it has shorter days and winter.

When the opposite happens, i.e., when the tilt of the Earth or North Pole is away from the Sun, winter occurs in our part of the world and we have shorter days, as it the case now.

Are the solstices always on the same days?

The exact dates of winter and summer solstices change each year.

The winter solstice can happen on December 20, 21, 22 or 23, but rarely on December 20 or 23. The last winter solstice of December 23 was in 1903 and the next one will happen in 2303!

The date of summer solstice varies between June 20 and June 22, depending upon the year and the local time. In 2018, summer solstice will occur in Pakistan on June 21, at 15:07 Pakistan time.


Stonehenge

Stonehenge, located near Amesbury, in Wiltshire, England, is perhaps the most famous ancient astronomical monument in the world. Built in three stages between 3000BC to 2500BC, it is made up of a ring of standing stones, each about 13ft (4.1 metres) high and 6ft 11in (2.1m) wide. The stones are set within a group of Neolithic and Bronze Age monuments, as well as several hundred burial mounds.

Stonehenge is carefully aligned on a sight-line that points to the winter solstice sunset, and winter solstice is considered to have been more important than the summer solstice to those who constructed Stonehenge.

Many people make the trip to Stonehenge to watch the summer and winter solstices, and the party stays on to see the solstice sun rise above the stones.


Solstices and ancient civilisations

The solstices have been observed and celebrated by different civilisations around the world for a long time. For most, winter solstice was a day to celebrate as it meant a return to warmer days.

Saturnalia: The pagan festival of Saturnalia was an ancient Roman solstice celebration dedicated to Saturn, considered the god of agriculture and time. At its peak observance period, it was a riotous week-long celebration from December 17 to 24, where everyone from the nobles to the slaves took part in the festivities.

It is generally considered that many traditional midwinter celebrations in Western culture, including that of Christmas, reflect some of the things that took place then, such as feasting and gift-giving.

Dongzhi: Dongzhi means ‘the extreme of winter’ or ‘winter arrives’ in Chinese, and it takes place on the shortest day of the year, about six weeks before the Chinese New Year and is considered as a day when everyone gets one year older.

Celebrated by the Chinese and other East Asians, the festival has its roots in the Han Dynasty (202 BC – 220 AD). Dongzhi is considered an auspicious day as it signifies the return of longer days and the corresponding increase in positive energy or yang.

As part of the celebrations, families get together and feast on traditional Chinese dishes such as glutinous rice balls, known as tang yuan and plain or meat-stuffed dumplings.

Shab-e-Yalda: This celebration of winter solstice, on December 21, is one of the most ancient Persian festivals that dates back to the time when majority of Persians were followers of Zoroastrianism. Yalda means birth, so its name means ‘night of birth’, and the celebration is also referred to as Shab-e-Chelleh.

The ancient Persians believed that on the longest night of the year, evil forces were dominant and the next day they celebrated the triumph of Mithra, the Sun god, over darkness. They gathered to pray, protect each other from evil, and would burn fires and performing charitable acts. Friends and family came together to make wishes, feast and read poetry, especially the work of the 14th-century Persian poet Hafiz.

Inti Raymi: In June when the winter solstice takes place in the Southern Hemisphere, in Peru, the Inti Raymi or the ‘sun festival’, is observed by the Incas.

Before the arrival of the Spanish and Europeans, the Incas fasted for three days before the solstice and before dawn on the fourth day, they gathered to wait for sunrise. They then performed some pagan prayers and sacrifice to the sun. After the Spanish conquest, the holiday was banned, but the 20th century saw the rival of traditional Inca practices such as this.

Toji: Some traditional practices are linked to the winter solstice in Japan. Farmers consider it a particularly important time as it signifies the return of a sun that will be good for their crops. Bonfires are lit to encourage the sun’s return and huge bonfires are lit on Mount Fuji on winter solstice.

Published in Dawn, Young World, December 16th, 2017