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Why Dec 22 has shortest day, longest shadow? Winter solstice explained


If your shadow seems longer these days, it’s because we’re heading towards the winter solstice—the time of year having the shortest day and longest night. Shadows stretch during this period due to the sun’s lower angle, especially noticeable in the early morning and late afternoon.

Winter Solstice, which will begin on Thursday, is that day of the year when we see fewest hours of daylight.(Representative)
Winter Solstice, which will begin on Thursday, is that day of the year when we see fewest hours of daylight.(Representative)

The word “solstice” comes from the Latin words “sol” (sun) and “sistere” (to stand still), according to Merriam Webster dictionary. It reflects the phenomenon where the sun’s apparent movement in the sky temporarily stops before reversing direction. Thus after this day, southern hemisphere starts tilting away from sun and northern towards sun. Here’s the science behind it?

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What is science behind winter solstice?

Now we know earth revolves as well as rotates around the sun which results in change of seasons and day night, respectively. However earth rotational axis is not straight but tilted at an angle of approximately 23.5 degrees relative to its orbit around the sun.

Imagine the earth is like a spinning top, and it’s a bit tilted. This tilt is what gives us seasons. Now, during the winter solstice, one part of the earth— northern hemisphere, leans farthest away from the sun.

Because of this tilt, sunlight has to travel through more of the earth’s atmosphere, making it weaker and spreading out. This makes it colder, and we experience shorter days and longer nights. The sun appears lower in the sky, casting longer shadows. So, the winter solstice is like the earth doing a little tilt away from the sun, giving us the coldest and darkest part of the year.

Also read- Summer Solstice: Unveiling the science behind June 21 as year’s longest day

Diagram explaining science behind winter solstice.(NASA)
Diagram explaining science behind winter solstice.(NASA)

When will India witness winter solstice?

The earth experiences solstices twice a year. In the northern hemisphere, the summer solstice (when this part is tilted towards sun) takes place around June 20-21, while the winter solstice occurs around December 21-22, says National Aeronautics and Space Administration (NASA).

According to Time and Date, in New Delhi, the sun will rise at 7:09am and set at 5:29pm, resulting in a daylight duration of just 10 hours, 19 minutes, and 17 seconds.


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