NASA illustration explaining the winter solstice and Earth’s tilt.
Credit : www.nasa.gov
Sunday, December 21, the world will reach the winter solstice – the shortest day of the year for everyone living in the Northern Hemisphere. It’s the date when daylight runs out faster than at any other point on the calendar and the night stretches on a little longer than usual. For many, it arrives quietly: darker mornings, early sunsets and that familiar winter feeling that the day barely had time to get started.
In the UK, the solstice will fall at around 3:03pm. In New York it arrives at 10:03am, in Los Angeles at 7:03am, just after 4pm in central Europe – including Spain- and later in the evening at 8:33pm in India. The moment itself is invisible – there’s no flash or sound – but from that precise point onwards something reassuring begins to happen. Each day will bring back a little more light than the one before.
Why December 21 is the darkest day of the year
The science behind the solstice is simple, but the effect is dramatic. The Earth is tilted on its axis, and during December the Northern Hemisphere leans further away from the Sun than at any other time of year. This makes the Sun travel low across the sky, cutting daylight hours to their absolute minimum.
Cities such as London, Toronto and New York will notice unusually short days, with sunlight limited to just a handful of hours. Further north, in parts of the Arctic, the Sun won’t appear at all, leaving communities in near-continuous darkness.
According to NASA, the changing seasons aren’t linked to how close the Earth is to the Sun, but entirely down to this tilt. As the planet continues its orbit, that angle slowly shifts again – and by December 22, daylight starts creeping back across the Northern Hemisphere.
In the Southern Hemisphere, it’s a totally different story. Countries like Australia, New Zealand and Chile will be enjoying their longest day of the year – experiencing the height of summer while winter reaches its deepest point in the north.
A moment humans have marked for thousands of years
Long before modern timekeeping, early civilisations carefully observed the skies and built monuments to mark the solstice. Some of the most famous sites in Europe were designed with this exact moment in mind.
At Stonehenge in England, the stones align with the winter sunrise, while in Newgrange, Ireland, sunlight enters a narrow passageway on the solstice morning and illuminates an ancient chamber built over 5,000 years ago. These structures show just how deeply people once lived in rhythm with Earth’s natural cycles – using the return of the light to mark both survival and renewal.
Today, space agencies monitor Earth’s movement with pinpoint precision, but the solstice still carries emotional weight far beyond scientific data.
How the shortest day can affect our mood
Modern studies suggest that the lack of daylight during winter can take its toll. Mental health specialists often point to the higher occurrence of Seasonal Affective Disorder (SAD) during darker months, when people report lower mood, tiredness, and disrupted sleep patterns.
Experts advise making the most of natural daylight during winter – even short walks outside can help – alongside staying socially connected and keeping a regular sleep routine. For some, light therapy has also become a popular option to counter the emotional effects of long, dark days.
But despite its reputation, the winter solstice isn’t something many people fear. For others, it feels strangely comforting.
There’s something grounding about knowing that this is the deepest point of winter, the longest night we’ll face – and also the turning point. From December 22, each sunrise arrives slightly earlier than the last. At first, the change is almost impossible to notice. Seconds matter before minutes start to show.
Over the weeks that follow, mornings grow brighter. Afternoons linger a little longer. Slowly and steadily, the light returns.
As conversations around protecting the planet continue to grow louder, moments like the solstice remind us how closely human life remains tied to Earth’s natural patterns. No matter how modern the world becomes, we still feel the pull of the seasons.
This Sunday December 21 brings the year’s darkest day – yeah- but also the quiet promise that brighter ones are already on their way.
