This concept of the shortest day and the longest night is known as winter solstice. It happens every year around December 21 or 22 in the northern hemisphere. In 2024, the winter solstice will occur tomorrow December 21 at 4:19 AM EST (2:49 PM ISTI). Let’s look at why this happened and how it affects different parts of the world.
The science behind winter solstice
The Earth is tilted in its axis by about 23.5 degrees. This title causes the seasons to change as the planet orbits the Sun. During the winter Solstice in the northern hemisphere, the North Pole tilts farthest away from the sun. This makes the sun’s rays hit the Tropic of Capricorn, which is located in the Southern Hemisphere.
Because of this tilt, the northern hemisphere gets the least sunlight on this day, making it the shortest day of the year. At the same time, the Southern Hemisphere is having its summer solstice, which is the longest day of the year.
Why does the winter solstice affect daylight?
The amount of daylight we observe in the winter solstice depends upon the geographical location of the land.
1. Near the equator: places close to the equator don’t observe much change in daylight throughout the year. They usually have about 12 hours is sunlight every day.
2. Mid-latitudes: cities like New York and London have much shorter days with about 9 days of daylight on the solstice.
3. Closer to the poles: places near the Arctic Circle like Reykjavik, Iceland, have very little daylight sometimes less than 4 hours.
4. At the North Pole: The North Pole doesn’t see any sunlight at all during this time because it’s in the middle of a long polar night.
Why is there a shift in the dates
The shortest day doesn’t compulsorily fall on one specific date it rather shifts to fall either on the 21st of December or on the 22nd of December. This is because a year on our calendar (365 days) is slightly different from a solar year (365.2422 days). To keep things on track the concept of a leap year was attached.
How Earth’s slowing rotation affects days and nights
Over time, the Earth’s rotation is gradually showing down due to the gravitational pull of the moon. This phenomenon is known as Tidal Braking, causing the length of day to increase by about 1.8 milliseconds every century. While this change is very small and not noticeable in our daily lives, it has significant long-term implications.
Historical Ties Winter Solstice
The winter solstice is not only a moment of scientific understanding but also a time of regional significance, celebrated and observed across the globe. This celestial event has deep cultural and historical connections, marked by sites such as Stonehenge in England, where the solstice sunrise aligns with the monument’s structure. In Mexico, Chichen Itza’s EL Castillo pyramid reflects the Maya’a advanced knowledge of astronomy, while Newgrange in Ireland captures the solstice sun illuminating the inner chamber, symbolizing renewal. Similarly, sites like Machu Picchu and Tikal in South America demonstrate the astronomical and agricultural importance of the solstice for ancient civilizations these sites highlight the enduring global connection to the winter solstice, reflecting its importance in both scientific and cultural contexts.
The solstice was also a time for festival and celebration,
- Saturnalia a festival celebrated in Ancient Rome was a time for feasts and giving gifts.
- Yule, celebrated by people in Northern Europe, included lifting candles and bonfires to welcome the return of longer days.
The winter solstice reminds us of our planet’s connection to the sun and the natural rhythms of life. It’s a special day to pause, reflect, and look forward to brighter days ahead