Which Day of December Marks the Shortest Day and Longest Shadows? Science Explains

Understanding Earth’s tilt, solar angles, and the fascinating phenomenon behind the shortest day of the year.

As December 22 approaches, you might notice your shadows stretching longer than usual and the days growing darker. This marks the winter solstice, the shortest day and longest night of the year in the Northern Hemisphere. Scientifically, the solstice occurs when the Earth’s axial tilt causes one hemisphere to be farthest away from the Sun, making the Sun appear lower in the sky.

What is the Winter Solstice?

The word solstice is derived from the Latin words sol (sun) and sistere (to stand still), reflecting the phenomenon where the Sun’s apparent movement across the sky briefly “pauses” before reversing direction. The winter solstice typically occurs on December 21 or 22 in the Northern Hemisphere, marking the Sun’s southernmost point in the sky.

Why Does This Happen?

The Earth rotates on its axis and revolves around the Sun, but its axis is tilted at an angle of 23.5 degrees relative to its orbital plane. This tilt causes different parts of the Earth to receive varying amounts of sunlight throughout the year, resulting in the changing seasons.

During the winter solstice, the Northern Hemisphere is tilted farthest away from the Sun. As a result:

• The Sun’s rays strike the Earth at a lower angle.

• Sunlight has to travel through more of the atmosphere, weakening its intensity.

• Days are shorter, nights are longer, and temperatures drop.

This tilt also makes the Sun appear lower in the sky throughout the day, which elongates shadows, especially during early mornings and late afternoons.

Solstices and Seasons

The Earth experiences two solstices annually:

• Summer Solstice: Around June 20-21, when the Northern Hemisphere is tilted towards the Sun, resulting in the longest day of the year.

• Winter Solstice: Around December 21-22, when the Northern Hemisphere is tilted away from the Sun, giving us the shortest day and longest night.

According to the National Aeronautics and Space Administration (NASA), while the Northern Hemisphere leans away from the Sun during winter, the Southern Hemisphere experiences its summer solstice, receiving more direct sunlight and longer days.

Winter Solstice in India

In New Delhi, according to Time and Date, the winter solstice on December 22 will feature:

• Sunrise: 7:09 AM

• Sunset: 5:29 PM

• Daylight Duration: 10 hours, 19 minutes, and 17 seconds

This is the shortest day of the year, with daylight duration progressively increasing after the solstice as the Sun’s path begins shifting northward.

Significance of the Winter Solstice

The winter solstice holds cultural and spiritual importance across the world. It marks the turning point where days begin to grow longer, symbolizing renewal, light, and hope. Historically, festivals like Yule in Europe and celebrations in India, such as Makar Sankranti (though observed in January), reflect humanity’s connection to seasonal changes.

Key Takeaways

• The Earth’s tilt of 23.5° causes the Sun to appear lower in the sky during the winter solstice.

• Shadows grow longer because sunlight strikes at a lower angle.

• December 22 is the shortest day of the year in the Northern Hemisphere, with minimal daylight hours.

As the Earth “tilts back” after the solstice, days will gradually lengthen, signaling the slow but steady return of warmth and light.