The Winter Solstice, or the shortest day of the year, is a remarkable astronomical event that happens every year. In 2023, India will celebrate this event on December 22⁴. But what causes this event, and why does it happen on this specific date? Let’s discover the science behind it.

The Science of Solstice

The word “solstice” comes from the Latin words “sol” (sun) and “sistere” (to stand still)⁸. This word describes the phenomenon where the sun’s apparent movement in the sky temporarily pauses before changing direction⁸.

The Earth spins on its axis, which is tilted at an angle of about 23.5 degrees relative to its orbit around the sun⁸⁹. This tilt is the reason for the change of seasons we experience throughout the year⁸⁹.

During the Winter Solstice, the Northern Hemisphere, which includes India, leans away from the sun⁸⁹. Because of this tilt, sunlight has to travel through more of the Earth’s atmosphere, making it weaker and more diffuse⁸. This results in shorter days and longer nights⁸.

The Shortest Day

On December 22, 2023, in New Delhi, the sun will rise at 7:09 am and set at 5:29 pm, resulting in a daylight duration of only 10 hours, 19 minutes, and 17 seconds⁴⁸. This day will have the least hours of daylight of the year in India⁴.

The sun appears lower in the sky during the Winter Solstice, casting longer shadows⁸. This is why your shadow may seem longer during this period, especially noticeable in the early morning and late afternoon⁸.

The Aftermath of the Solstice

The bright side is that from this point on, the days will start to get longer until Midsummer’s Night in about 6 months⁴. However, even though there is more energy from the sun, the latent temperature of the Earth makes the air temperature slow to react⁴. This phenomenon is known as seasonal lag⁴.

Conclusion

The Winter Solstice is a reminder of the intricate dance between our planet and the sun. It’s a time when we celebrate the shortest day and the longest night of the year. So, on December 22, 2023, as you celebrate the shortest day in India, take a moment to marvel at the astronomical accuracy that makes this event possible.