The ZSD happens twice a year at the places, which fall between the Tropic of Cancer and the Tropic of Capricorn.
Published May 10, 2023 | 1:52 AM ⚊ Updated May 10, 2023 | 6:14 AM
People in Hyderabad observing Zero Shadow Day. (Twitter/@Shanti_Vineet)
Hyderabad witnessed a unique celestial event Zero Shadow Day (ZSD) at 12:12 pm on Tuesday, 9 May.
The ZSD is a phenomenon that occurs when the sun’s position is directly overhead and thus no shadow on vertical objects can be seen.
Bengaluru saw a ZSD at 12:17 pm on 25 April this year.
Several Hyderabad citizens took to social media and posted videos and pictures of the phenomenon.
The ZSD happens because of the tilt of Earth’s axis and its rotation around the sun.
The axis about which Earth rotates tilts at an angle of 23.45 degrees to its orbital plane and the sun’s equator.
ZSDs happen twice a year at places that fall between the Tropic of Cancer and the Tropic of Capricorn.
Here are some of the videos and pictures of the ZSD posted on social media by people in Hyderabad:
#ZeroShadowDay #Hyderabad
Hyderabad witnessed a rare phenomenon called the Zero Shadow Day (May 9 at 12:12 pm) pic.twitter.com/Uk6s2VsUcL— Faiz Baig (@FaizBaig) May 9, 2023
Students and Staff of Department of Astronomy, Osmania University,Hyderabad have gathered to witness the astronomical phenomena 'Zero Shadow Day’ on May 9, 2023 at 12:12 PM. @osmania1917 @prof_ravinder @KTRBRS @IAU_Outreach @asipoec @awb_org @astro4edu pic.twitter.com/qv0m1BmXQu
— Dr.D.Shanti Priya/Department of Astronomy (@Shanti_Vineet) May 9, 2023
Zero Shadow Hour #Hyderabad 12:12 PM to 12:14 PM pic.twitter.com/IjUeZt7Nj8
— Sibghat صبغت (@SibghatK) May 9, 2023
As per the Astronomical Society of India (ASI), ZSDs take place when the sun’s declination (Earth’s axis results in a daily variation of the angle between the Earth–sun line and Earth’s equatorial plane) is similar to the latitude of the location and its rays fall exactly vertical to an object on the ground leading to no shadow of that object.
People can do a simple experiment can be done at home to enjoy the Zero Shadow phenomenon.
A flat surface needs to be arranged directly under the sun.
After that a white paper should be fixed on the flat surface and around noon a tall opaque object like a Polyvinyl Chloride (PVC) pipe or a metal tumbler should be placed vertically on the white paper on the flat surface.
The shadow of the object will be seen after that.
It should be marked. After that, the shadow of the object needs to be observed every five minutes and mark them.
Once this is done, the shadow can be found moving and exactly at the time of the ZSD phenomenon.
During the ZSD, the circumference of Earth can also be calculated by comparing the shadow length at a distant city situated in the same longitude at the same time of ZSD.
