Researchers have observed that a certain day behaves differently from the rest of the year. This is a recurring event where daylight seems to hesitate, shadow overstretch, and nighttime appears to be longer than usual. Although many are oblivious to this day, with the longest night of the year, this article breaks down its essence and why it’s important for Earth’s annual orbit.

What causes the seasons we experience on Earth?

When you think about it, seasonal changes are one of the most inevitable on earth, but what causes them? How is it that we experience autumn, spring, summer, and winter while everything seems still? Over the years, scientists have explained how these changes are caused by Earth’s orbit.

Generally, Earth’s orbit around the sun isn’t an upright spin. Instead, Earth’s rotation is a rather tilted fix. This is what governs how light reaches different parts of the Earth’s surface, and hence, how we experience daylight and nighttime differently around the world. With a fixed distance between Earth and the Sun, these changes produce what we know as seasons.

Now, as Earth continues through its tilted orbit, it gets to a point where daylight begins to shorten more than usual. This is usually when the Earth reaches an extreme point in the northern hemisphere. Here, the sun arch has reached its lowest point, causing minimal daylight. This is often experienced in winter, and it is known as the Winter Solstice.

What is the winter Solstice, and when does it occur?

The winter solstice is the first day of winter in the Northern Hemisphere. It is the day with the fewest hours of sunlight throughout the year. It marks the beginning of astronomical winter, which occurs once in the Northern and Southern Hemispheres. Whenever one of Earth’s hemispheres is experiencing the winter solstice, the other is experiencing the summer solstice.

Taking into account Earth’s tilted rotation around the Sun. Whenever the winter solstice occurs, half of the Earth is orbiting far away from the Sun, while the other is rotating towards it. The sun rises and sets at its most extreme south, causing daylight to reduce and the night sky to lengthen beyond what is normally experienced, like this extremely rare supermoon, amplifying coastal tides.

At the end of the solstice, the sun begins on a low part again. Although this might not be visible to everyone, the days begin to grow longer and longer again until we reach the point of the summer solstice. This would be the first day of astronomical summer and the longest night of the year. For 2025, the winter solstice is expected to be on Sunday, December 21st.

Ancient cultures have revered the longest night of the year for centuries

Before scientists began to measure these solstice days, astrologers from ancient civilizations had often revered them for several reasons. For them, it was not just an astronomical event; it was a time when agricultural cycles were shifted. When darkness overshadowed light, they offer rituals and rites.

How the winter solstice affects the month

The winter solstice marks one of the remarkable times of the year. However, one must understand that being the shortest day of the year doesn’t signify the coolest day of the year. Instead, it shows us how the sun’s and the Earth’s tilted rotations relate. With a shift towards an extreme point, the sun stays farther away than usual until the end of the day.

However, while winter conditions may become intensified after the solstice, the long trajectory would have changed. As Earth continues on its path around the sun, the planet begins to recover and set towards the spring. Hence, the solstices can be seen more as an overnight reset, although it may take months to eventually unfold, just like this new historic astronomical event turning day into night.