Odisha Witnesses Rare Astronomical Event ‘Zero Shadow Day’
Odisha has been one of the few states in India to have perfectly aligned conditions to witness a rare astronomical phenomenon called the Zero Shadow Day. On Friday, state capital Bhubaneswar played host to the same, wherein no shadows of objects kept in the daylight were observed due to celestial conjunction.
At all regions lying between the geographic Tropic of Cancer and the Tropic of Capricorn, the phenomenon is seen twice a year while the sun is at its highest point in the sky. As the sun becomes positioned exactly overhead, the shadow of all objects on the ground disappears. This, however, lasts for a very short span (typically a few minutes), before the sun shifts out of the vertical alignment to a slightly angular orientation in the sky with respect to the object.
To commemorate this event, the phenomenon has been popularly named Zero Shadow Day – indicating a phase wherein no shadows are visible.
Bhubaneswar witnessed the event on Friday when the Zero Shadow moment lasted for three minutes, starting at around 11.43 AM.
Subhendu Patnaik, who heads the Pathani Samanta Planetarium in Bhubaneswar as Deputy Director, explained that this phenomenon occurs whenever the rotation axis of the Earth is favourably tilted at an angle of 23.5° to the axis of revolution around the sun. He also added that Cuttack would observe a similar phenomenon on Sunday.
In technical terms, during the sun’s apparent North to South and South to North shifts, there are two days in a calendar year when the sun’s declination and the latitude of a place within the tropics align briefly, making shadows disappear for a short while.
In Odisha, subject to clear skies, different districts may observe the Zero Shadow Days starting from May 21 to June 2.