Bhubaneswar: Odisha capital witnessed Zero Shadow Day at 11.43 am for three minutes on Friday.
On Zero Shadow Day, the Sun does not cast a shadow of an object at noon, as the sun comes exactly overhead, known as zenith, over all the regions along between the tropics-the Tropic of Cancer and the Tropic of Capricorn.
It is generally witnessed twice a year for places between +23.5 and -23.5 degrees latitude.
Zero Shadow Day
“For every point on Earth between the Tropic of Cancer and the Tropic of Capricorn, there are two Zero Shadow Days (ZSDs) every year. As the Tropic of Capricorn passé well below the Indian land mass the event can only be observed between Kanykumari to Tropic of Cancer which passes through central India little above Odisha,” said Dr Subhendu Pattnaik, Deputy Director of Pathani Samanta Planetarium.
Timing At Other Places Of Odisha
The event is observable in all parts of Odisha, but on different dates and time. Bhubaneswar citizen already experienced on May 21 at 11.43 am. Again they will witness at 11.53 am on July 22.
Cuttack- May 22, 11.43 am and
July 22, 11.53 am
Burla – May 28, 11.52 am and
July 15, 11.56 am
Rourkela – June 2, 11.58 am, and
July 10, 11.56 am
Balangir- May 23, 11.54 am, and
July 20, 12.04 pm
Baripada: May 31, 11.41 am and
July 12, 11.49 am
Do We Need An Equipment to See?
“We don’t need equipment to see. We can observe the event at our place also for which place any symmetrical object like bucket, pole, cardboard box, bottle etc vertically on a plane surface outside under the direct sun. Observe the shadow just before the noon on the ZSD. You will find the length of the shadow will go on decreasing and will disappear for some time then it will reappear and will go on increasing as sun moves towards west,” he informed.
Why A Zero Shadow Day?
“We can observe that sun does not rise in exact East or set at the true west every day. It rises only in the true east direction only twice every year that is around March 21 and September 21 when sun moves exactly over the equator,” said Pattnaik
The point of sun rise moves from south to north from winter solstice (September 21) to summer solstice( June 21) known as Uttarayan and it moves back from north to south in a motion called Dakshinayan, he added.
This happens because Earth’s rotation axis is tilted at an angle of roughly 23.5° to the axis of revolution around the sun. The sun’s location moves from 23.5°N to 23.5°S of Earth’s equator and back. All places whose latitude equals the angle between the Sun’s location and the equator on that day will experience Zero Shadow Day with the shadow beneath an object at local noon, said Pattnaik.
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